Oil Pressure Query - During a spirited run

Hi Everyone - Yes probably another boring oil pressure query. I've laid out the post the with all I know Info 2004 996.2 C2 manual with 122,000km (75,000mi) Rebuild / refresh by previous owner at 114,000km (70,000mi) No mention on the invoice for new/refurbed scavenger pumps No mention on the invoice for new/ refurbed oil pump New oil pressure sender 2,000km ago (previous sender was sending oil pressure needle bouncing like it was at a night club) New 997 oil pressure relief valve / spring 5W-40 Motul X-Cess GEN2. 2,000km on the oil. Oil was recommended by The Motor Oil Geek (Lake) as other options are not generally available here in Aust. Like Driven etc, Pennzoil etc. 71 degree thermostat Engine runs very cool. Even after sustained high RPM wide open throttle the temp needle never gets past vertical. So probably 85-90C? Engine in excellent condition. In 5,000km of ownership zero oil consumption. Running oil level at max on the in-car gauge and on the stick (they correlate to each other). I can confirm it is the 996.2 dip stick that measures less oil than the original 996.1. AOS is new Porsche part. I�m getting Oil pressure drops mid corner and they not high G corners. Sustained corners, yes. I�m not tracking the car. I�m just driving it with purpose through fast sweeping country roads. The car is well warm (take 90 minutes to drive to the playground). Here�s some notes Whilst hot (more than 30 min of driving) and on the freeway at around 2800rpm (110 kph) oil pressure will be around 4 bar. Maybe a little higher. Water temp will at or just below 80c (180F) When starting to play the oil pressure is very good, Well above the 1 bar per 1000 rpm. Idle (I had to pull over to wait for traffic to clear) was almost 2 bar. My hand is in the way when turning left but I noted that the pressure would be ok but a slight increase in turn-in I would see it drop to 2 bar from around 4 bar. cannot comment if it was early in the run or later (ie hotter oil?) I think I was getting the drop on left or right longer sweeping type corners. I * think * it was worse when the oil was hot. I determine oil is hot when I�m at or a little below 1 bar per 1000rpm and / or oil pressure at idle is at 1 bar After my run yesterday I did note that my oil pressure was 2.5 bar at 2,800rpm when back on the freeway. Pressure slowly lifted back to around 3.5/4 bar as I assume the oil cooled. The tyres are brand new PS4S and the type edges are not feathered at all. I.e I�m hardly leaning on the car. I know what 1G lateral feels like and can hit that with easy in my Golf GTI or Audi A4 Avant wagon. I was nowhere near 1G lateral in the 996 on the weekend So I�m after some ideas on what to do that isn�t crazy $. I know about UAOS and you can run more oil. I know about deep sump and there are several offerings etc. these are all great ideas but have, for me, draw backs one of which is I don�t want to have a lower sump. I like the clearance and some of the roads I need that clearance. If it did come to UAOS and the Ultimate sump that is 8,000AUD investment for a car I�m not tracking nor likely to ever track. I just like fast twisty roads. I'll go out and play like this once a month or so. Here�s some of my thoughts but open to suggestions Since the car was apart � did the engine builder (maybe) didn�t put things back in the sump as they should be? I�m not sure what is it a standard sump has in terms of baffles. Perhaps worn out? note It was Skip that picked that this car�s scavenger pump was 180 degrees out when I first purchased the car and had AOS issues. Is there uprated 997 parts that should be swapped in? Oil pump / scavenger pumps perhaps not at their best / lesser efficiency ? Referencing this post https://rennlist.com/forums/996-foru...l#post14492975 how would I know this might be an issue for me? Reference this post https://rennlist.com/forums/996-foru...l#post14176044 is it worth just replacing? In-sump AOS old and need replacing? Do I look at retro X51 option. Guy in the UK called Martin Hill has developed a two stage scavenger pump that is for the right bank with a X51 pipe requiring drilling into the heads (super not keen on that) Go to a 10w-50 oil. But not sure why a thicker oil reduces aeration? I suspect I�m dredging up know issues but honestly I was barely pushing and I don�t want to already feel like I�ve out stripped the car�s capabilities

I have chased this issue with no success. Suggestions are to upgrade to UAOS and get a deeper sump to just protect engine if pressure really is going that low. I started this thread about low pressure and tick at idle, but around page 4 (of 10) it shifts to my finding drops of pressure in moderate turns. https://rennlist.com/forums/996-foru...ticking-4.html I decided to buy another 996 for track/canyons, install the UAOS, and just accept the 996s drop pressure in turns... or at least some do... I did also try 5w50 mobil 1 and it didn't do anything.

Oil pressure drops are pretty easy to solve for but you have to spend a couple of bucks to increase the volume of oil in your engine. First thing you can do is put on the UAOS Track on your car so you can run and safely process 1-2 qts more oil in your engine above full. Second thing you can do is to either put on a 2qt deep sump or go all the way and put on the UIDS. The 2qt deep sump will give you 2 additional qts of oil in the engine and the UAOS Track will give you 1-2 qts more. Thats a total of 3-4 more qts of oil above full. The more oil you have, the less oil pressure instability. OR you can go all the way with the UIDS which is the industrial strength sump solution since it makes sure that oil is always under the pickup. Third thing you can do is run heavier oil like a 10w50. Bottom line is our M96s need more oil quantity to solve for oil pressure instability amd oil starvation. But the only way you can run more oil is to have an AOS that can safely process it. The factory AOS cannot. The Porsche Motorsport AOS cannot. The only one that can is the UAOS Track. So this is where you need to start. Hope it helps.

Thanks for the comments / thoughts so far. I started thinking. Slakker / HarTech are known engine builders. So what do they do when they rebuild a M96 engine for a customer? What are they doing to mitigate this on their builds I wonder

Quotes source post: 19914440

there�s some good info from Slakker here: https://rennlist.com/forums/996-foru...l#post19854349

My 996 has the UAOS track drain version along with an LN Engineering 2 quart extended sump . I also changed the 996 oil return tubes in the sump to the 997 version . I fill 12 quarts of oil and no matter how hard I push her in the twisty mountain roads near me I do not see any pressure drop . I use 5w40 Liqui Moly oil . I am very happy with the results . I do not track the car so the results may be different on a race track .

Quotes source posts: 19914006, 19914440

Short Answer: You're using oil with too low of a viscosity. As oil heats up, its viscosity drops rapidly, and it's a compounding issue: - The oil pump becomes less efficient with thinner oil. - Oil flows through bearing clearances faster. - Viscosity modifiers break down over time, making the oil even thinner. Additionally, the 996's oil drain-back system is a bottleneck. Quick Fixes: 1. Use Motul 300V 10W-60 - 50W is better, but 60W is ideal. - Running 40W or thinner oil on track can void our engine warranties�it�s that critical. - The PCA originally followed advice from aforementioned well-respected source (who taught me most of what I know about oil) but saw 987.1 engines failing in club racing. They later analyzed one of our race engines and found oil pressure stayed above 40 psi in corners, while others dropped into the low teens. 2. Upgrade to 997-style drain backs - The 996 swirl pots restrict oil return to the sump. - A 996.1 customer was still seeing mid-teen oil pressures on track with Dominator SAE60. After switching to 997 drain backs, oil pressure never dropped below the mid-30s. 3. Consider a sump upgrade - If you don't want a deep sump, the FVD .5L sump adds an X51-style baffle, and performed better than stock in our testing - For track use, we still recommend the Hartech racing sump (or UIDS) 4. Bonus: Add a third radiator - Helps keep coolant and oil temps in check. Downsides: - Your engine may sound tickier at idle. - Otherwise, every component gets better protection. Additional Notes: - A hot engine should hold 4+ bar oil pressure at 3000 RPM. Porsche spec is 3 bar, but we replace the oil pump if it�s under 4. - Oil flows sump → pump → filter, so scavenge pumps often look better than the oil pump, even after an engine failure. - I haven't tested Martin Hill's two-stage scavenge system, but I respect his work. What We Do in Our Builds to Address Oil Starvation: - Hartech Motorsport big-end bearings (12% wider, improved oil retention). - Loctite 574 to seal oil galleys not sealed by factory (e.g., crank carrier to crankcase, lifter carrier to cylinder head). - Strict bearing/journal clearance tolerances to minimize leak paths. - No oil-fed IMS bearings (robs pressure from critical areas).

Quotes source post: 19914476

the last recommendation on IMS is interesting. So we are better off with the factory solution?

Quotes source post: 19914499

I�d recommend upgrading to the larger M97 IMS bearing during a rebuild. This was Porsche�s solution to one of their biggest design flaws, and it effectively resolves the issue. We�ve seen M97 IMS bearings with 200K and even 255K miles that are still in great shape. If you have a smaller bearing IMS (as I do) and aren�t ready for a rebuild, replacing it every 60K-80K miles with a new SKF or NSK (6204-C3 for single row)�without seals�is the best approach. Just removing the seals increases the rating of the single row bearings from 11k RPM to 18K RPM and will not suffer from the grease drying or burning up. For street driving, I�d also recommend using a high quality oil such as DI50 or Motul 8100 15W-50 which will further help protect the bearing. IMSB failures happen gradually and can be detected through used oil analysis. If they do fail, the only real damage we see is a $350 oil pump replacement, as all debris sheds before the oil filter. On the other hand, the popular oil-fed IMS bushing (which isn�t a bearing) poses a risk�if the oil feed line snags or kinks, it can seize and destroy the IMS in addition to sending debris to the oil pump. We�ve also monitored the oil pressure in the feed line and found it to be lower than the system pressure when the engine is hot. This suggests that the IMS side of the line is less restrictive than the oil filter tap side, meaning it is bleeding off system pressure.

I drove to the PCA Tech Tactics East event yesterday morning. One feature of my route is a freeway ramp that takes me from US22 eastbound onto PA33 northbound. It's a big, unusually long, right hand turn. I was behind a minivan, which is to say I was not exactly pushing big G-forces. I'd estimate that it took me 10-15 seconds from beginning to end. By the end of the turn my oil pressure was fluctuating. Same thing happened last year. Moral: it doesn't take high G-forces to starve the oil pump, it just takes time. (High G's might accelerate the process.)

Quotes source post: 19914587

great, thanks for the explanation and offering your hands-on experience with these engines, which is refreshing in comparison to what one sees on 997 forums these days.

I agree with most all Slakker said here...the oil pressure instability issue CAN be solved in the M96 engine but must be understood fully if you want to use the most cost efficient means on your particular application/engine.... The most effective "bolt-on" ways to solve is (1) more oil capacity .. 1 a. UAOS Track 1 b 996.1 dipstick 1 c Deeper Sump (2 )Oil control 2a UIDS 2b dual scavenge pumps 2 c 997 oil returns (3) . oil viscosity 3a, use thicker oil 50w-60w 3b center radiator 3c bigger CSF radiators 3d bigger oil cooler We learned a lot from the ****show of a thread on oil instability that lead to the invention of the UAOS Track Version which is the first/best "bolt-on" solution in over a decade ( Deeper Sumps were previously the first/best) ...and also started the development of the UIDS System......I continued the work with $4k Data Acquisition Equipment on am M96 on the Track to perfect the UIDS SYStem and to gain other insights into the oiling system of the M96... The 3 basic things that effect oil pressure stability (1) oil capacity (2) oil controll (3) oil viscosity ..they are each important in stable oil pressure in different and dynamic ways that are not always so obvious...I'll give a simple brief overview of each without going deep into the Technical/Dynamic Physics (1) oil capacity.. This is pretty obvious that more oil is better at keeping from starving for oil but has always been a problem for the m96 and the ONLY thing you could do was just install a deeper oil sump ....due to smoking from inefficient AOS System the oil level was actually "lowered" in the 996.2 and 997.1 engines.... The development of the UAOS and then the UAOS Track Version over the last erveral years has allowed the oil levels to be raised continually ..originality to full levels then to 996.1 levels then to 1.5 to 2 qts over full levels...This made a HUGE difference when coupled with a deep sump as it provides up tp 4 qts additional oil availible to the oil pump. (2) oil control This is where it gets really Dynamic because it is control of moving oil with pressures and Gravity forces in play that make it difficult to explain or follow because things are happening in tenths of a seconds and constantly changing over a wide range of variables.....But I will be brief and simple ( although not Technical) The oil baffles in the factory sump or x 51 baffles do not do a good enough job for every circumstance to keep oil in the center of the sump for the oil pick-up...During higth G or long turns the oil in the center of the sump will run out because The Sump is 14 inches wide ...the UIDS on the other hand has Twin Tunnel Port at each side of the 14 inch wide Sump and can pick-up from either side when G forces dictates or can use both at once ....So it is not trying to "control" the oil but rather switching to where the oil IS...and is always in the deepest/lbest oil availible.... The main oil pump in the M96 is very large and capable of pumping much more oil than the engine needs and is capable of emptying the oil sump very quickly ..There are 58 leak paths/flow paths that are lubrication points the main oil pump delivers oil to ....This is the flow of oil out from the Sump to 58 different lubrication points so small increase in wear in each of these 58 points will have a dramatic effect on the flow of oil out of the Sump per second.....and also an increase in temperature of the oil will have a dramatic effect and the amount of oil that will leave the Sump per second.....and then this oil that has left the Sump must be returned back to the Sump before the level in the Sump has gotten so low that it effects oil pressures... The only thing I disagree with Slakker on is the oil fed IMS Solution...With 58 lubrication points adding one more to 59 will have a negligible effect on the flow as a whole....it's just math....I've added Turbo oil fed lines to oiling systems 40 years ago and has been done millions of times with no detrimental oiling effects......a small wear of only half a thousandths in 58 lubrication points will have a much much more effect on the oil flow.... (3) oil viscosity Oil viscosity plays a big role in the M96 much more than in standard Wet Sump engines, due to the Integrated Dry Sump System ....Typical Wet Sump engines use Gravity to drain the oil back to the Sump...pretty simple right ?? Gravilty is always at play to help or hurt the oil returning to the Sump....In the typical Wet Sumps the Gravity is ALL that is needed to get the oil back to the Sump, and the Sumps on Wet Sump Engines are always narrow width wise so just some simple baffles will work good........But on the M96 with the Integrated Dry Sump , it rely s on Gravity to return the oil from the crankshaft, but needs Scavange pumps to return the oil from the heads/cams/lifters..ect...This is where the oil viscosity plays a big role..... The thinner the oil the more gets pumped into the heads and the more that HAS to be returned .. So the thicker the oil the more that STAYS in the Sump on the IDS .. This also means that the COOLER the oil the THICKER it is , ..So the cooler we can keep the oil the MORE there will be in the SUMP of the IDS .... So upgrading the Cooling System or Oil Cooler can have a big effect on the viscosity in a particular application even when using thick oil like 50w-60w... Recap :::: I broke these down to help explain them but they all actually work together and effect each other in some ways....These are just "bolt-ons" that can be done to CURE oil pressure issues.......IF you have not done ANY of these things then don't expect to have stable oil pressure in turns.....

Thank you everyone. There's a lot to digest here so I've been sitting on it. @SlakkerRacingDev Query around oil weight. I don't know anything so lets just start with that. What I've always believed is an oil can be too thick and fail adequately get into tight tolerance spaces (bearings, between rings and cylinder in my head) which leads to excessive wear? Ie So why would the factory recommendation be 40 weight if Film thickness wasn't a concern? On the back of this - I was told that having too high oil pressure isn't good either. So a thicker oil would mean a higher constant pressure and cause other issues? Would 60 weight be the recommendation for track work and 50 for canyon carving? or 50 weight is ok but really "everyone" should be using 60 weight @SlakkerRacingDev @Porschetech3 I really appreciate the concise list of 'this is what would help / solve'. Looking at the list this would be the best for a track car that is going to see uber high temps with sustained 5000-7000rpm over a number of laps. For example if I were to add UAOS, UIDS alone that is $4500USD or around 7,200AUD plus install time. And that's before getting to perhaps radiators and duel scavenge pumps etc so starting to get into serious money and I'm wondering if that's only for track time. What would be the middle ground do you think? So here is my train of thought 997-Style drain backs (part number? is it a straight fit?) Replace sump. with FVD X51 (*) Motul 300V 5W-50? or 15W-50 ? or is the advice Motul 300V 10W-60 With the sump - given that I'm not talking track time and only canyon carving with PS4S - would the advice still be 'You're wasting your time not to go with a deeper sump" in which case would the next logical step be FVD X51 style with their spacer? or hartech/UIDS is the only option. Thanks

In your first post you stated that you saw the oil pressure drop from 4 bar to 2 bar after turn-in. That alone is asking for a UIDS. The UIDS kit includes the 997 drainback tubes. I would caution against deeper sumps for the sake of ground clearance. The UIDS itself hangs a bit lower than the original sump plate, but has more ground clearance than other sump extensions. If your car is lowered, you better be riding on some stiff springs to prevent bottoming out on your sump. But, since most canyon roads are quite bumpy, a stiffer coilover setup may be detrimental to overall grip.

Quotes source post: 19918902

- 997.107.016.00: Oil Return Tubes x2. - For aggressive street/canyon carving, we've seen great results with 50W oil and an FVD sump. - I think Porsche's recommendation for a lower weight oil (0W) was to minimize idle ticking. Heavier oil might make the engine tickier at idle, though it smooths out by around 1200 RPM. Plus, it could help boost mpg to meet EPA standards. - I rely on oil pressure data to determine fill levels and viscosity for our track cars. - I also recommend using Used Oil Analysis to see what your engine really prefers. - The bypass valve keeps pressure under 100 PSI, but I primarily use oil pressure data as my guide. - Oil temperature is the key factor in choosing the right viscosity. Most people don't realize how quickly the viscosity drops with temp....

I ran an X51 style baffle in my sump, 2003 C2, and still had oil starvation in sweeping turns on the street. That was with full oil fill and with UAOS prior to the development of the track drain - which I now have, just have not installed. My choice at the time was to get the UIDS for ultimate protection. After that - same sweepers, no oil starvation. I also switched to the 996.1 dipstick and thus higher oil fill levels. As I have time, I will get the track drain installed, just other priorities right now. -Tom

Quotes source post: 19918998

Brandon, great data. Thanks for posting the analysis. I am blown away by the Dominator 60 stats. Everybody should save a copy for reference.

Quotes source post: 19918998

Thanks Brandon, this is some great info, i feel this issue is subjected to so much smoke and mirrors. Is the FVD sump in question the 0.6l version? or are we talking of the 2l? I'll be doing the return pipes, fvd sump and 50 oil for the road in the future, although i cant say I've noticed any pressure drops (on my gauge) on my usual weekend blasts so suspect i have an x51 baffle or similar on my ex Japan early 996.1

The first question you have to ask is , Is my engine loose, tight, or just right .... How do you tell ?? You put an accurate oil pressure gauge on the head port ( not the facory electric gauge) and with Mobil 1 0w-40 oil at exactly 90C oil temp and exactly 4k RPM you record the oil pressure.......If the pressure is above 4 Bar you are just right, if it is way above 4 Bar the clearances are tight...if it is at or below 4 bar the engine is loose.... I was in charge of a Fleet of 996's used at the Porsche Driving School at Barber Motorsport Park with the M96 engines .. They were all new with Factory "N" spec tires and didn't have oil pressure drops on the 996.1's ..If the tires were changed and as new/better tires were used and engines got more miles on them is when the oil pressure issues started... Porsche was also very inconsistent on oil levels.... The first 1999 specs were 8.75 qts oil. There was a TSB to immediately change the oil fill level to 9.3 qts...No reason was given just that it was to take effect immediately......Then there were issues with Smoking on hard turns on the Track and the "Unofficial: word from Porsche was to run the oil level at mid-norm on the dipstick, and then with the 996.2 in mid 2002 the oil level was lowered again to 8.75qts and also the Motorsport AOS was designed for the M96 by Mann+Hummell , they are also the ones who designed/manufacture the plastic intakes and OEM AOS systems for the M96 and others.. One quick word about the Porsche Motorsport AOS ..It is just an OEM AOS with a larger body/tank that holds more oil that really should be returned back to the Sump ..It has the same return and the exact same thin diaphragm in it and the same efficiency........The Internet Lore that it is more robust is false it has the same diaphragm and efficiency and while it does hold more oil to help keep from the intake, it effectively lowers the oil available to the oil pump thereby increasing chances of oil starvation... No Need to worry about running thicker oil, a 20w-50 or 10w-60 will be ok to use unless the ambient temps get to below 0F...The thinner oils are for gas mileage and emissions only... Your oil viscosity choice should be determined by application...your engine internal clearances , the ambient temperature and your running oil temperatures.. I know most Porsche owners want the most economical solution , I get that, but you will need to equip your car with gauges and yourself with knowledge to see "what you can get away without" to find the most economical solution for your application......When I was in the hunt to set the IHRA World Record I searched for the best parts, or had them Custom made, and then just worried how to pay for them....The upgraded parts to solve all issues with the M96/7 are available...

Quotes source post: 19918998

The Valvoline VR1 isn�t highlighted in green, despite being marked with an asterisk. Is it actually recommended for Street/AX use? And why isn�t Millers CFS 10W-60 recommended? It appears to maintain its viscosity as well as the others.

Quotes source post: 19920619

Mostly snobbery on my part, lol. The VR1 Full Synth is a good oil, but I�ve seen the conventional version completely break down after exposure to high track temps. I�m running M1 15W50 in my 996.2 daily right now, but the formula isn�t what it used to be, and I’m planning a rebuild in the near future. The feedback I�ve gotten on Millers is that it doesn�t stand out in UOAs. In contrast, the oil experts I consult consistently rank Motul 300V and DI products a notch above everything else. They argue that in brief periods of oil starvation, these oils continue protecting the bearings better than others. Similarly, if there are early signs of bore scoring, 300V and DI can slow or even stop its progression. As for the FVD sump, we recommend the 0.5L version for street use. I�d assume an X51 baffle upgrade would yield similar results. It�s an improvement over stock, but it still requires keeping the oil at the max fill line to be effective. On track, it only started performing decently when overfilled by about 1.75L hence why we only recommend it for the street.

Quotes source post: 19919085

Yes, impressive stats for the Dominator 60, however, Amsoil recommends their Dominator SAE60 for drag racing and tractor pulling, both short bursts of enormous horsepower, then drained. Since I don't do that, I think I will stick with DT40. Your Millers shows some great stats.

Quotes source post: 19921936

Hah, i gotta get a tractor then! Millers was a very good oil. Lake suggested that I move over to DI for it's qualities, suggesting that it was good on both the street and track at high temp. So far it's been very good with DI40 in the cold months and DI50 in the warm months. Oil temps don't get real hot at Blackhawk being a small track. But Road America with the carousel and 3 long straights is a different story. After looking at the stats I sure wish there was a DI60. Maybe they have it and I haven't found it yet.

Quotes source post: 19921936

Lol. Nice dig. If you don't drive aggressively or on track, I'm sure DT40 works great for you. Otherwise, I'm guessing you are doing it blindly without data logging or you wouldn't still be doing it. Cheers!

Quotes source post: 19921001

Okay, gotcha. Do you plan on using M1 15w-50 with your rebuilt engine?

Wow, lots of good info here. I just bought my first 911 after searching pretty consistently for a couple years. I had delved into the IMS issue of course but just now learning about the oil pressure/starvation issues. I purchased a 2000 Millenium Edition 6 speed with 156k miles that had a IMS failure at 137k and then an engine rebuild where they honed the cylinders and replaced the piston rings. Because that engine rebuild was 6 years ago, and I couldnt determine which IMS bearing was put in, I sent to ProTech Motorsports in Greenville, SC to have them do a post-purchase inspection. They found no metal in the oil filter, bore-scoped the cylinders and they looked good. They took a sample of the oil and sent that off. They did an oil change and used Liqui Moly High Tech SAE 5w-40. A few questions for the experts here: 1. This car is going to be my daily driver for the time being, not a track car or autocrosser, but I do like to drive fast whenever I can. Regardless of if that Liqui Moly High Tech 5w40 is the absolute best oil for my needs/uses and the M96 oil pressure issues, I guess I should continue to use that same oil for a few cycles , while continuing to do the oil analyses, as a control, so we can accurately assess the results of the oil tests? 2. As stated this is a 996.1, MY 2000, built 10/99. So I guess I have the "early" 996 dipstick? (My car is not a "early, early" 996, as in, built in 97, 98 or early 99 up to 8/98.) 3. What is the most cost-effective modification I should make to the engine in order to safeguard against oil starvation/pressure drops during the occasional, extended, "high"-G turn that I may encounter on the streets? Thanks in advance for any and all input.

Quotes source posts: 19921960, 19922157, 19922360

Robin Poole from Driven stopped by the shop last week, and we discussed this very topic. They used to offer a 60W oil but discontinued it. However, he mentioned that Lambo and Nissan GTR owners have also been requesting it, so there�s a chance it could make a comeback. Maybe we should start a campaign and have people email [email removed] to request they bring it back as DI60? 😆 No, I�ll switch to DI50 afterward. I might switch sooner if the rebuild gets delayed�like the rest of my personal projects�but I still like M1 15W50 as an inexpensive, short-interval �clean-out� oil when I get a new-to-me car. 1. I�m a big advocate of using data to let your engine tell you what it wants. Even if it contradicts my suggestions, always follow the data. The oil expert I trust most has been pretty critical of Liqui Moly, so I�ve traditionally recommended against it. However, we just finished a rebuild on a 255K-mile 997.1S where the owner had been running Liqui Moly 10W40 since purchasing it at 47K miles. Texas car, mostly highway miles, and he didn�t hesitate to drive it aggressively�yet the cylinder walls looked great. While a single data point is anecdotal, it�s still pretty dang impressive. 3. Based on the data I�ve seen, thicker oil filled to the max line and upgraded drainbacks will give you the best return on investment. If running at the max fill line causes oil in the intake or startup smoke with your driving style, UAOS would be the next step. After that, an upgraded sump, followed by a third radiator, in that order.

Quotes source post: 19922562

+1 But I would say that if your AOS needs to be replaced, which it eventually will, go to the UAOS Track version which has the drain to the sump/oil filler tube. It will allow you to run an additional 1-2 qts of oil over full, which is the key to solving for oil pressure stability. The M96 likes lots and lots of high quality oil.

Quotes source post: 19922562

Will do. there is one (1) bottle left for sale in Australia thru JEGS.

Quotes source posts: 19922562, 19922618

Thanks guys.

Don't forget to change your water pump as well. No need for cracked heads when you can easily prevent it. The M96 is pretty damn easy to keep running strong on and off the track with a couple of bolt on parts and frequent oil changes with high quality oil. Problem is alot of folks ignore doing a few simple things for whatever reason. For sure, it costs a couple of bucks. Believe me when i tell you, there is nothing better than a well sorted 996. Any money you spend to keep it running will bring a huge smile to your face ever time you start it up and drive it.

Quotes source post: 19921962

The DI40 has been highly recommended for its ability to fight bore scoring in my stock 996.2 3.8 and since my racing days (No tractor pulling for me, just wheel-to-wheel road racing.) are over, it is doing a great job. The Used Oil Analysis says all is good at 57,000 miles, so I am happy.

Hi Team Ok - I've decided to the following * FVD X51 style sump * 5W-50 Motul 300V * 997 drain back pipes While I'm there - worth replacing the oil pickup tube? Also I am on the fence about replacing the radiators with CSF.... or adding a centre radiator. Its just canyon carving. Not track work. the centre radiator changes the original look... and the two CSF radiators are not cheap delivered to Oz and I'm unable to find a local reseller. I can always change latter if need be. Or am I wasting my time by not doing them? I have noticed that my water temp runs much cooler when the AC is on vs no AC. If that helps / means anything

Running the AC turns the fans on low, so the is always air moving through the rads. My temps are lower as well when running AC. Whether you change rads depends on the temps you get to. New rads will improve cooling, but if you are already cool, there�s no need. My spirited driving, with CSF rads, results in 190F max.(I also have a 160F thermostat.) I would expect the 3rd rad is only needed for extended RPM time above 4K, as on a track. Yes, upgrade the oil return tubes.

Also, check to see that both your fans have a low speed. A very common problem is that the resistor that creates the low speed burns out. Each side has one. Turn your AC on and check that both fans are on. If not, you�ll need (a) new resistor.

Well I started this thread and thought I'd do a quick update. I decided to go with the FVD x.51 style sump and change to Motul 300v Competition 5W-50. This has all just taken place this week. I also replaced 6 injectors as I had some fuel dilution and the only logical answer was the injectors. I had them pulled and they were down from factory with one injector sticking shut. Anyhow. 50km in and what I can say is going from Motul X-cess 5w-40 GEN2 oil to the 300V 5W-50 there is SOO much more oil pressure. Usually after 30 min of driving i.e engine is hot the oil pressure would be around 1.5bar with the 5w-40. now 2.5bar on the 5w-50 One thing that is slightly annoying is the sump plate seems to sit a little low compare to the cross member so now a little worried about hitting it. So I guess a bash plate in the future.

Quotes source post: 20086005

Where did you find 5W-50? I checked Pelican Parts, ECS Tuning, and FCP Euro. FCP has 15w-50 which I may go with since you get credit sending the used stuff back. But I'm open to other options.

We are testing Molygen 5w50 in a few street only cars and recommending 300V 15W50 for street/ track day engines. Both are available from FCP.

is it normal for oil pressure gauge to read half psi with ignition in accessory mode (before ignition)? 5psi at cold, 1.5psi at hot idle. 2.5psi to 3.5psi @ 2500rpm highway speed. I noticed pressure drop 1-2psi on gauge in normal cornering around town and during hard braking (0.5-1psi).

Quotes source post: 20090013

What you are calling PSI for the numbers 1-5 on the oil pressure gauge is BAR ;;( 1 BAR = 14.5 PSI ) No it should not read 1/2 when key on,.. it should read 0 ..( replace the sending unit) With 0w-40 OEM oil it should be about 1 BAR per 1k RPM At 90C oil temperature....( 4 BAR at 4k RPM at 90C with 0w-40 oil weight).

Quotes source post: 20090147

your right, I meant bar. Thanks, will replace the sending unit. It was on 5W-40 Liqui MolyGen. It feels like the engine does not like this oil very much? The digital dipstick keeps reading different oil level after short drives, but it reads normal oil levels if left to sit long enough. Recently replaced oil pan, and tech noted sump/pick up was good at that time. Could the fluctuating oil pressure be the spring/scavenging pump orientation? Also, had a stall one time when it sat in traffic for 45 min on a very hot day. Coolant temperature reading was exactly on the last white stroke past the "180"F (oil pressure was below 1 bar, around 0.5 bar at idle)

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The digital dipstick is truly only valid once a day, after the oil has had overnight to return to the sump. Checking thru the day will have you chasing levels. I can, even thru out a day, not starting the car at all, just simply turning the key on, see different levels reported by the digital dipstick - even within 10 minutes. If fluctuating in turns, it is easy to uncover the oil pickup on moderate G turns running factory oil levels, even with the x50 baffle. You need to be 2 quarts over factory fill if you want to not have loss of pressure on the street in moderate G turns with factory pickup. To run 2 quarts over and not risk hydrolock thru AOS sucking oil into the intake and into the cylinders, you need the UAOS with track drain. If you want more safety, add the UIDS. -Tom

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So aside from the sender going bad, everything else being exhibited is normal? I still don't get why it stalled out that one time in traffic... does it overheat that easily grant it was 45min of pure stop & go traffic but still...

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Check your radiator fans. Make sure both run on low and high speed. If not - repair the issue (fan or resistor). As to the stall - stalled on it's own - or did you happen to err with the clutch? I know when I am in stop and go traffic for some time, slowly creeping - it is easy to "oops" the clutch release and stall the engine. -Tom

Ha, that does remind me that I find it easier to stall when it�s really hot out, while trying to move from a standstill by only releasing the clutch. It never happens when the engine and air temperature is cold.

Quotes source post: 20091678

yeah, why is that? Never have this issue with my other sports cars even ones with highly strung engines.

I�m not really sure, but if I had to guess I�d say the dual mass flywheel may be a factor.

When engine cold it needs and gets more air and fuel via the ECU to overcome higher friction of the cold engine (and idles a little higher too, i believe). This gives it enough torque to drive off with only releasing the clutch. The hot engine doesn't have the higher friction and the little extra torque it has in reserve, which is less than in above case, when idling is used in part to drive the generator which is harder to turn as the radiator fans are running to keep coolant temps in check. The remaining of the 'little extra torque' is too low to get the car moving hence the engine stalls.

As the original poster I thought I'd update on where I've ended up. Thanks for the input from Brandon and Skip as usual. Wealth of knowledge. This past weekend I went for a squirt on what you'd call canyon carving. Not the original roads that caused me to witness the pressure drops but similar. So here's what I ended up doing Motul 300V Competition 5W-50 (switch from Motul Xcess 5W-40 Gen2) FVD x.51 style sump (standard one that adds 0.5L. Not the additional 2L capacity) 997 drain backs to replace the swirl pots New pickup tube (was only a handful of $$$ so freshen it up) 6 new bosch injectors (oil sample had 3% dilution. after testing the 20 year old original injectors one was sticking shut until a slight bump in voltage was added. Replaced the one injector and had it flow tested. The new injector was 30% better flow than the other 5 so ended up replacing all injectors) Car already had the low temp thermostat. The drive was in 10-15C temp range which will obviously help. What I noticed was from around 3500RPM I was up around 5bar of pressure. Water temp barely crossed 80c often showing just below the 80C line. I've completed 1100km of city driving and 400 of weekend fun. Will oil sample at 2,000km for the fuel and see how the 'race' oil is coping with city driving. Ps I would have liked Skip's sump but I don't track and often driving down windy twisty dirt roads as I use the car for classic (navigational) rallying

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Justin, congrats on the improvements. Very good steps. For sure, getting your arms around the issues of any model Porsche is like drinking from a fire hose. Per your original post, dont forget that if you want to solve for oil pressure, you gotta get MORE oil in the M96. A 0.6 sump is nice, with the X51 and plumbing, but you gotta actually overfill it and be able to effectively "process" the oil so it doesnt get into the intake. The only way you can do this is with the UAOS w/ Track drain. The factory AOS cannot, nor can the Motorsports AOS. If it was my 996, I would figure out how to budget for it and pounce on buying one when the trade policies of both of our countries provides a favorable opportunity. I've watched too many folks here on Rennlist gloss over the importantance of having an AOS that actually works and provides effective benefits. Remember this, the 0.6 sump you bought is pretty much worthless because your factory AOS cant process the itty bitty addition of 0.6. It cant even process factory oil level recommendations which is why Porsche tells everybody to run a half quart less. So, to put it simply, if you want to effectively solve for oil pressure, you gotta get more oil in the M96. To get more oil in the M96, you gotta have an AOS that can process it. The only AOS on the market that can process the extra oil is the the UAOS T. Assuming your engines "blow by" is in spec (see Skips thread on blow by"), by combining the UAOS T with the 0.6 qt deep sump, you can run 10-10.6 quarts of oil in your engine. A hell of alot better for oil pressure stability than 8-8.6. For sure, heavier high quality oil is also a necessary ingredient. FWIW, just trying to help you and every other m96 owner. Dont forget to change your water pump if you havent already. The UAOS T and a fresh water pump mitigate 2/3 major faikure points. An upgraded IMSB is the third. Easy as hell fixes. Best

Water pump was replaced with Porsche part at the same time the low thermostat was installed. Owned the car 15 months and its been a journey from the previous owner. It has a brand new Porsche AOS. UAOS is down the track. I need to breathe from all the recent $ spent.

@justinbAUS So are you calling you oil pressure drops fixed ?? The Steps you took are (1)increased viscosity from 40 to 50 (2) added.5 qt oil volume ...is that all ? I would suggest taking at least one more step for a "Safety Margin"... I like helping people cure their oil pressure drops even if they only take baby steps as long as they are diligent in making SURE it is cured and then one more step for a Safety Margin... I would normally advised to take a "big swing" at it instead of "baby steps"...but I understand being frugal and risk management.....

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Hi Skip, Totally solved? Based on everything I've read from yourself and others I believe have the right intentions... no. but significantly minimised at a price point? hopefully yes. I used this as my logic ( https://rennlist.com/forums/996-foru...l#post19918998 ) where Brandon mentioned that they've seen good results with the FVD X51 style sump during caynon carving. the FVD sump adds 0.5L yes, but also has X51 style baffles. I'm not running sticky tyres and not going to the track. The FVD sump was $1000 delivered to Australia. Your UIDS was going to be 6500 delivered to Australia plus would need to add a sump guard. What would be your one more step?

I'd imagine the next step was Skips UAOS.