oil pressure question

I have a 2001 all stock 996 C4, except for the 1/2 quart more sump space. 68k on the engine, 104k on the car. The used engine was installed by a previous owner. Last year I put new chain guides in as well as a new oil pump, OP switch, and AOS, and several other small things while the engine was out. This past weekend I went to Thompson Speedway to and drove in a HPDE event. I drove the car very hard compared to the previous year. I was in the 5-6500 rpm for most of the laps. All went well the first day. All looked good. OP when hot was at around 2500 rpm and was just under 4 and just about 1.5 bars when at ildle. Engine temp was just past vertical to the right a bit, say just after 12 on a clock. Air temp was in the 50's. The second day I was driving again very hard, same sort of RPM. Air Temp was a little warmer. The engine temp was higher, maybe ay 1 o'clock on the dial, but not an unfamiliar level. But after the first 30 min run I pulled in and heard tappet noise from the passenger side, and the OP was down to 1 bar. I reved it up to 1200 RPM the noise stopped and the OP went up to 2.5. I shut it down and let it cool. Oil level was as it should be. No smoke, no leaks. Coolant level was optimal. I let the car cool and started in for a second run and there was the normal OP and no tappet noise. I did a warm up lap and then 3 hot laps and after the 2nd lap I saw that the OP was pretty low, maybe 3.5 at full revs, and it dropped fast when shifting down to close to 1. I pulled in. The tappet noise was not there but at idle the OP was at 1. I let the car cool and drove home. Kept the revs down to 3000 and the engine ran fine and at normal temperatures. OP at 2500 was around 3.75-4. I drained the oil and pulled out the Pressure relieve valve. It's about 1 year old, and is the 997 version. I might have found something in the valve tube, but am not sure what it was and if it was above or below the top of the valve. I refilled it with oil and started it. OP cold was 5. As the engine got to normal temperature, the OP was 1.6-1.7 at idle, and around 3.8 at 2500 RPM. I drove the car several miles at temp, not too hard and it was great. No issues. Oil sample sent to Blackstone Labs. Does anyone have any ideas why the OP dropped so much at the higher temperatures? What else can I look at?

What brand and weight oil are you running?

What oil weight are you running ? How many miles on the oil ?

If you don�t have a center radiator on your car, then you need to install one. I�m not sure if a low temperature thermostat would help in this case, but I always like to recommend using one.

Have you checked the oil filter for metal particles? Do so if you can. Get coopduc's oil temp display. I rate that as more important than a 3rd radiator and I have both.

Quotes source post: 20064041

You probably won't want to hear it, but you gotta get more oil quantity in your engine with the UAOS track if you plan on doing DE or AC to boost your oil pressure. In addition, run higher weight oil. I run DI50 and my 3.6 likes it. The UAOS track will allow you to run an extra 1-2 quarts of oil over full, which is really 3-4 more over full including a deep sump. See my explanation below on what I run. The quantity will depend on your blow by numbers. See Skips "Blow By" thread as well as his "UAOS" thread for info. So to put it simply, counting your 0.5 qt semi deep sump, you may be able to run 1.5 - 2.5quarts of oil over full of higher weight oil which will help. For sure, keep testing your oil, check whats in the filter when you change it, etc. Oil pressure is something you have to solve for in both the 3.4 and 3.6. Very easy to do with more oil with the UAOS and a deep sump. If you decide to attend more DE events, I would recommend a 2qt deep sump or the industrial strength UIDS. For a point of reference, I run a 2qt deep sump and the UAOS track on my car w/ DI50 on the track. What this means is i run 4qts more oil over full or 12.5 qts total. 2 quarts extra from the deep sump and 2 qts more from the UAOS Track. My oil pressures on track are pretty stable under G with all the oil. The key is the UAOS because it can process all the extra oil. Neither the oem AOS nor the Motorsports AOS can do it. Good luck with your next steps.

Quotes source post: 20064538

^^^This

Thanks all. I hear the heavy weight oil message, but that does not really explain why the OP is so different at the higher temp. Is is just that the oil is thinned out too much by being hot? I have been using 0W40 and put in 5W40 when I changed the oil after the track day. I have considered the 3rd radiator and doing new FCS alum radiators at the same time to boost cooling. I have the .5 qt sump extension, but perhaps I should do the different sump baffles and oil pick ups. I worry a lot about ground clearance with the 2 Qt sump. . So I wait for the Blackstone analysis before I take any new steps. If there is no metal from the bearings in the oil I will try the added cooling and heavier oil, and look into the sump options.

The simple answer is the longer you run the engine at speed on the track, the hotter the oil, the thinner it becomes and the lower the pressures go. Heavier higher viscosity oil helps and well as more oil quantity in the M96. Quite frankly, I would NOT spend any money on a deep sump until you upgraded your frail and suboptimal aos. That is your WEAK link. If you plan on tracking your car, get it off your engine as fast as you can. You are not doing your engine any favors w/ the factory AOS. After you do this, then consider adding a 2qt sump or the UIDS which gives you more ground clearance. Either way, upgrade your oil to something heavier.

Here is a very useful matrix from @SlakkerRacingDev comparing different oils at diverent temps. Extremely insightful. @hardtailer recomendation for @Coopduc ​​​​​​​oil temp gauge was dead on. Knowing what your oil temps are at different tracks and at different time intervals on a particular track can be very helpful in understanding what oil to run, if you need more cooling as well as when to get off the track as a "just in case". It sure helps if you run a higher viscosity, heavier weight oil that can withstand higher temps than one which can't.

@Coopduc oil temp gauge. This is a must have to measure oil temps.

I�m surprised you achieved such high oil pressures using 0W-40. I assumed you were already on 5W-50 given those pressures. You�re going to want step up to 5W-50 for track work. Or maybe switch to Driven DI40 for track, if you don�t want to try a 50 yet. I second GC996�s suggestion for the UAOS. There�s multiple benefits: 1) it eliminates the coolant line at the factory AOS location, eliminating a potential source of coolant-oil intermixing 2) The replacement separator diaphragm is tougher and easier to change 3) it�ll allow you to overfill the engine oil (and more oil will prolong the time before the oil heats up) 4) purchasing the optional �Track-drain� kit will route the oil in the accumulator back to the sump, ensuring that you have adequate oil where it needs to be. Sure, the oil temperature gauge is a nice thing to have, but I stand by my recommendation for better cooling. When the gauge tells you that your oil is hot, all you can do is back off the pace. With a third radiator, you may not even need to back off. If you decide to upgrade to CSF radiators at all 3 locations, you could also upgrade to the larger 997 oil cooler (at least I think that�s the correct one). It has a larger interface for the oil and coolant to transfer heat. But you need the third radiator - at a minimum - for this upgrade, or else you will risk bore scoring. Best bang-for-the-buck: I think you can see major improvement with the addition of a center radiator and switching to stronger engine oil. You could also delete your AC condensers to improve air flow through your side radiators (this costs nothing, except maybe being charged to evacuate your AC refrigerant).

In my experience (max ambient temp of 30�C/~90F) the 3rd radiator is not the game changer one would wish it to be. The bottleneck being the coolant/oil heat exchanger that is too small to transfer the heat from the oil into the coolant resulting in too high oil temps. ETA: using the bigger 997 heat exchanger will help and then the added 3rd radiator makes sense. As such I agree with @996love The oil temp display obviously won't change that but as 996love rightfully said, you can only back-off but at least you can do so in time.

Oh I see now. I stand corrected. I thought the addition of a third radiator would make a meaningful difference.

Quotes source post: 20064632

Yeah, pretty much. When oil gets really hot, it gets thin, and that�s where the oil film becomes less effective and metal to metal contact can occur and cause engine damage. Which is why race oil is generally thicker and more tolerant of extreme heat.

And the thinner oil also moves away from the oil pump pickup more quickly, increasing the risk that the pump sucks air.

Quotes source post: 20064632

I've been chasing this problem for years. I found lots of other random posts about the same thing. This thread I started is a mix of low pressure and tapping plus low pressure in turns, but you might find some tidbits. https://rennlist.com/forums/996-foru...e-ticking.html I tried over filling (just temporarily) and 5w50 and nothing seems to matter. When it gets to a certain temp, the OP is low (mine even turns on the OP light) and the tapping starts. Indy said the tapping is just a lifter stuck, and bc the oil pressure is low it ticks (something along those lines). I changed my water pump and put in fresh Porsche coolant, and added the LN low temp thermo, but at the end of the day, these engines will run up to whatever operating temp they need to when hot. Forgot to mention, I have two 1999 996s, and the low OP only happens on one of them. So that left me even more confused

Something to think about as we discuss this topic. There is a big difference between track driving and street driving as it pertains to oil pressure stability. A huge difference. As it pertains to the track. Just one (1) additional or less quart of oil can greatly influence oil pressure levels under G. For sure, 2, 3 or 4 quarts can make an even bigger difference. So can the weight of the oil especially at high temps due to the M96 oil pump being able to pump so much oil out of the sump at such a high rate. The thinner the oil is, the faster it goes, so run thicker oil. If you dont have enough oil in your sump, you will experience oil pressure drops until the oil drains back into the sump. A good example of this is when I was working with Skip to figure out oil quantity to run in my 3.6 using the UAOS Track. I have been running a 2 quart deep sump with the Motirsports AOS since the beginning of time which gave me 10.5 quarts of oil versus factory 8.5. 10.5 is certainly better than 8.5, but not as good as 12.5. But the Motorsports AOS could not handle 12.5. But the UAOS T could. So when I first replaced the MS AOS with the UAOS T, I put in 11.5 quarts of oil. Certainly smoothed out the oil pressure drops and raised the overal oil pressure level, then after talking with Skip, I added one more quart for a total of 12.5 which was the magical number. Then I went to DI50 from DI40 and it looked even better. From there, I had a PCA buddy who was a fellow instructor and club racer take my car around the track for a full session at speed so I could sit in the passenger seat and watch oil & water temps as well as oil pressure as he pushed it hard. The combo of 4qts extra oil with higher weight oil is key. I am patiently waiting for Driven to release their DI60 to test. I suspect it will provide further incremental improvements.

Quotes source post: 20065688

Probably an upgraded oil cooler would be necessary in your case.

Quotes source post: 20065793

The solution was to just buy another 996 for hard pushing and keep the cabriot for date nights

I'll keep my fingers crossed that your Blackstone Report comes back good, I hope you "Dodged the Bullet" ..!!! You say that the lifters were clicking after you saw some oil pressure drops.....That means the lifters got some air in them and also means the bearings got some aerated oil at the same time... Lifters have to stay full of solid oil with no air else they will click, Main bearings can handle 50% air/oil for a short period and Rod bearings can only handle 30% air/oil for a short time ... The M96 is a unique engine that was built to a price point like 95% of all production engines, but is has some serious engineering to it ..People who have said it is just a "Wet Sump" for decades don't understand the engine dynamics.... Any "Flat" engine can't depend on Gravity to help return oil to the Sump and the M96 uses an Integrated Dry Sump to help return the oil to the Sump and does a good job at high RPM on straightaways/Autobahn ect.. but during high G force cornering it struggles, and even says so in the Owners Manual... A lot of engines have failed due to this...... but many many things can be done to help and some upgrades can cure the issue.. Heat is one of the main issues with any engine and even more so on the M96.....especially Oil Temperature.. There are too many things to cover in one post but no one needs to fully understand them all to trust the Science behind the good advise that has already been given.. But since oil is the lifeblood and everyone loves to talk oil, here is some common since oil facts...Yes the oil film protection gets thinner the hotter the oil gets and will not protect or cool the vital parts, and if the oil gets too hot it will breakdown. To put it simply as far as thermal protection and film strength a 50 weight is better than a 40 weight and a 60 weight is better than a 50 weight......and a group 4 synthetic ( POA) is better than a group 3 synthetic ( hydrocracked) ,, and a group 5 synthetic ( Ester) is better than a group 4 .....then you have the additives ZDDP , Moly, and the new "Nano Particles" on top of that that reduces friction that also reduces/keeps oil temperatures down .. Bolt-on upgrades UAOS/UIDS/deep sump add more oil,,,, more oil is better and also control the oil so the pick-up doesn't suck-up air... I hope your power unit lives to fight another day !! ....

@jdsculler did you get your Blackstone Report back ?//

Test Not back yet. Due in 5 days or so. Got the center radiator kit and it goes in this weekend. will clean again the radiators. Did some spirited driving this week and temp was over 190 so i need the cooling no matter what. Got some 5w50 mobile 1. Looked at all the brands and weights and there are more opinions than fish in the sea on brands but all say at least get thicker oil. I did Mob 1 because it has the porsche certification. Track day on the 20th. Going to be in the 80’s so it will be a good test. Will watch temps and pressure carefully.

How much total oil do you put in your M96 ?

Quotes source post: 20089242

Watch you pressures on the track. I can push mine down to 1.5 in turns just on canyon roads. On the track you can really starve the engine depending on what tires and pressures you're running. I did one track day in mine before realizing I needed to do some upgrades. I installed a UAOS on my second 996 which I'm prepping for more track use. Eyeing the UIDS too, but $$$. If I start to really get sticky tires and overwhelm the system, I'll probably upgrade to dry sump.

Quotes source post: 20090332

Yea, the UIDS is $$, but it can do things no other Sump can do. Plus has more ground clearance than all 2 qt Sumps and is fully O-ringed ( no messy silicone to deal with or skew the UOA reports) The only Technical/Functional difference in the UIDS/IDS and whats called a "True Dry Sump" is the Tank/oil reservoir.......and there is no place to put a 3 Gal tank on a 996 street car .. and no real good place on a 996 Race/Track Car but it can be done with some "long hoses" ( put it in the back seat area)

Third radiator made all the difference in the temp. Stayed just a bit over 185 no tappet noise after a session. Used mobile 1 5w50. Porsche approved so it was an easier solution. Too many oil choices. Oil test showed above normal iron and aluminum. So early bore score. no smoke or other noise and i saw none when i borescoped the engine. Will do another oil test in a couple months.

yes the UIDS is $$$, but much less dollars than a rebuild. I have UAOS and UIDS on all my NA motors. I never worry about low oil pressure in turns. All my cars have three CSF radiators also. In the end it is risk management. If you want to drive your car hard, do the things to protect the engine. It is much less expensive than fixing a blown engine.

^^^^^^ Yes exactly !!! Don't "expect" a Carrera to do GT3 things ..... But you can "make" a Carrera do GT3 things without spending GT3 $$$$ ...and still have a nicer "Street ride" that a GT3 can't give With the right upgrades the Carrera can do GT3 things with way less $$$ than buying and maintaining a GT3 ..... Here is one right here .. @KJinDC a stock 3.4 with UAOS/UIDS in a Carrera doing "GT3 things"...oil pressure stable as a Rock ... You Tube Would you mind posting your Used Oil Analysis ? I want to see how well you "Dodged the Bullett" ..

Quotes source post: 20065758

Is there any protocol here for measuring oil levels? I�m confused. There�s always residual oil in the motor, so how are folks accounting for this? Are we measuring from the �max� mark on the dipstick? So max mark plus X extra quarts equals the overfill amount? Or are people just dumping in X number of quarts per oil change and reporting that number? And are we talking the 996.1 dipstick fill level or 996.2 level when we say �overfull.� I�ve got a UAOS (and a UIDS in a box to be installed) and trying to figure out where the hell I should be on my (backdated) 996.1 dipstick.

Quotes source post: 20115777

Here you go, from Skip. 996.1 oil stick in a 996.2.

After the oil has been drained, I fill it up with 12 qts. Probably 0.5 qts still in the engine it goes to the 2 qts over full line. So I am probably running close to 12.5 qts. Just to level set, I am running the UAOS Track and a 2 Qt deep sump. Yes, i do plan on going to the UIDS. Skip will have to tell you what the total quarts would be with the UIDS and UAOS Track combo. My guess is 11.5 total vs 12.5 with a deep sump.

Quotes source post: 20115777

There is always residual oil inside the engine after draining.( 20min min )....This amount is to be disregarded and doesn't matter except on a new or rebuilt "dry" engine... The recommended quantity for UAOS/UIDS for ANY M96/7 engine is 11.5 qts .....The dipstick and/or dash gauge is for reference only ..( some engines don't even have a dipstick) .IF unsure of quantity, drain and refill... This recommended quantity can be increased by .5 qts IF the engine has passed the blow-by test here ... https://rennlist.com/forums/996-foru...=engine+health

Quotes source post: 20115748

I also own and track a 996 GT3 and I agree with Skip on the difference in maintenance costs between my 99 996 C2 and 04 GT3. Additionally, since I added the UAOS and later the UIDS, the oil pressure has been rock solid at Summit Point, VIR, and PittRace. I swear by those products. Thanks Skip!!! -KJ

Quotes source post: 20116331

Congrats man! Love to see guys driving their 996s like they should be driven with all the RIGHT bolt-on parts!

That�s good to hear. You may need a couple more data sets to be sure it�s completely solved the issue. No doubt the extra radiator helps cool the coolant, but the oil cooler temp capacity remains unchanged.