3.5bar at 5000rpm, anyone?

In the manual for my 2000 3.4l it says "With a warmed up engine and at a speed of 5000rpm, the engine oil pressure should be approx. 3.5 bar". My pressure (brand new and verified sensor) is +5 bar already at 4000rpm when properly warmed up. The wording in the manual "should" tells me I should probably aim for 3.5bar at 5k rpm? Does anyone try to follow this?

So you want to lower your oil pressure? Not a good idea. It is what it is. I think that the 3.5 bar is a minimum recommendation. Also, type and weight of oil makes a difference.

There is a lot of benefits to running the correct pressure rather than too high/low. Too high creates unnecessary heat, it reduces the flow thru the engine and thus reduces the cooling. For our M96 it also directly, proportional, put more load on the IMS bearing, since the pump is driven from the IMS shaft. What I read there is a general rule among engine builders to have 10psi oil pressure for every 1k rpm. 50psi is roughly the same as 3.5 bar.

As the user of the car the only reasonable thing you can do is to change the viscosity of the oil to alter the pressure. That's my question, anyone is doing that? chasing the correct pressure rather than just 'as much as possible'.

I'm at 146K miles on my car and original engine. I was a true believer in Mobil 1 0W-40 for years. Then I changed to Liqui-Moly 5W-40. My engine just seems to sound better and run better. The new recommended "Classic Porsche Oil" for our cars is 5W-50. That will definitely increase your oil pressure over what was recommended 20 years ago with the Mobil 1 0W-40.

All our engines are worn to different degrees and may have different clearances already from factory. As such, two engines with the same oil can have different oil pressure. So, everyone should not use the same viscosity...especially taking in consideration the way the car is driven. To determine the correct viscosity you should follow this 3.5bar at 5000rpm....if I understand it correctly. I guess the M1 0w40 will give 3.5bar at 5000rpm on a fresh engine since Porsche recommends it.

This just came up in another thread so I checked mine this week. After driving at highway speeds for 30 minutes I found that 5000 rpm was 4 bars. I'm running Liquimoly Top Tech 5w40. I feel good about having more pressure rather than less. What you are doing seems like it would be a good thing.

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4 bar at 5k I would say is within 'approx.'. Do you have a fresh pressure sensor? My old toped out at around 4.2 bars. Easy to test, just rev it out and check that it can show 5+ and that it shows 0 when the engine is off but ignition on.

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Mine does start at 0 and does hit 5 bars. I think it's ok.

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If you have the "right" IMS bearing not sure that would make any difference...

Keep in mind the oe oil pressure sending unit is not very accurate, I would buy a new one & compare the reading's.

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Very roughly calculated you reduce the bearing life by 1/4 by running way to high pressure like I am right now compared to 3.5bar at 5k. If you bearing life is 100k hours, well 75k hours is well beyond anything else in the engine. Then, what is the 'right' bearing?

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That spec is there to tell owners when it�s time for rebuild. If you want lower pressure, you�ll have to open up the engine and change the tolerances. That�s a bad idea. If you change the oil viscosity too much to get lower pressure, that�s a bad idea too. Be happy you have 5 bar, that�s healthy.

just observed on the dash gauge, however accurate that is: idle(800): 1.3 2000rpm: 2.6 3000rpm: 3.2 4000rpm: 3.8 5000rpm: 4.3 key switch on, engine off: 0.3 engine has 95000 miles Driven DT40 Oil Observations made after warm up driving and 5 miles at freeway speed Engine coolant temp indicates 190F Max I've seen on this gauge is 4.8 when engine is warming up Could not find a Durametric value to monitor. It seems it's available on the 997.2, but not for 996 Before the DT40 I was running M1 5W50 and the pressure was higher, sorry, no noted values Nick_L, how did you get your sensor verified?

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It's a completely different story but I have cycled between three sensors(one was an OEM Porsche) and all three show the same pressure. By this, I know my sensor is good. In addition, done the test as described above. Doesn't need to be more serious than that. A sensor which measures 0-5bar and outputs to an analog gauge is a very rough measuring system, nothing high precision/accuracy in it. Since your sensor shows 0.3 when off and maxes out at 4.8, it's probably time for a new sensor. Mine is zero when off and 5.5 when starting cold with 5w40, all three showed this behaviour. Everything in the manual refers to this pressure measuring system(sensor, cables, gauge etc) , so don't try to calibrate it, then the values of the manual will not apply any more. If you are interested in knowing more accurate absolute values you could hook up a separate pressure sensor and check.

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There is nothing in the manual which says this is the rebuild pressure, that's you making things up. If you want lower pressure, you run a lower viscosity oil. Lower viscosity oil does not mean less protection as commonly thrown around. The manual recommends anything between 30 to 50 weight.

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Given the above statement, why are you stressing about 3.5 at 5,000rpm then?

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Ask an engine builder what they say when oil pressure is too low. Unless there�s something obviously broken, a loose engine would have to be rebuilt at this stage. You�re only going to get 1/2 bar for every 10w change, so thicker or thinner oil is NOT the solution. It�s a workaround, and it�s quite useful, but eventually, the engine is going to have to be rebuilt.

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There are two things here: 1.How good/reliable is the oil pressure system, can we use it as a guide getting to 3.5bar? 2.Should I/we try to achieve 3.5bar at 5000rpm? My answers 1.Yes, I believe the system is good enough if the sensor is recently replaced. 2.I believe so and I'm curios if someone is already doing it, hence this thread. I'm having pressure drop issues on street tires with my car at the moment. It started happening after I changed the chain tensioners, which gave a noticeable increase in oil pressure. My best guess is that the oil pressure is so high that it frequently pushes oil thru the pressure relief and aerates it to a point where pressure is lost. While looking for solutions about pressure drops I've read several deep sump threads and came by this one--> https://rennlist.com/forums/spec-box...mp-or-not.html It has pressure data from a Cayman race car on track, and pressure is around 3.7bar at race speed. That is even less than the 3.5bar at 5k.

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1.) Not very 2.) No I should have time later today to come back and explain how oil systems work, and why you are misinterpreting what the Manuel is saying. Getting from 5 to 3.5 bar at 5,000 RPM is not what the manual wants you to do.

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Yes, of corse, but that's not why the 3.5@5k is in the manual. It's to guide the owner telling him when pressure is too high/low. Here on the forum people keep quoting their idle oil pressure, better would be pressure at 5k rpm since it's specified in the manual. On a side note, have you ever heard/read about an M96/M97 being rebuilt because it was too loose and nothing else?

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Looking forward to learning something. I'm not saying I'm 100% correct, but with the knowledge I have right now it points in that direction.

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Everything below is in reference to street driving, not tracking or racing. So let�s start with how the engine oiling system is designed. A new 996 M96 engine has a positive displacement oil pump and machined engine tolerances such that the oil pump should give 5 bar at cold start and 5 bar at 5000 RPM when hot. There is no such thing as �too high oil pressure� as long as: 1.) The engine is within proper spec 2.) The bypass valves are operating properly 3.) The right oil and filter is used 4.) The temps are in line The positive displacement oil pump in the 996 is not a variable one like that found in the newer engines, so the only way to control pressure and volume is to use a bypass valve. At normal operating temperatures, low RPM speed doesn�t need a lot of volume or pressure, but as engine load and speed increase, you want increased volume and pressure - to a point - and then any additional volume or pressure is not good, I agree. However, Porsche designed the top end high pressure of this system to have a this taken into consideration, even as the engine starts to wear. Wear: The tolerances inside the engine - how large are the holes that control oil flow in the crank, cams, bearings, rods and bearings, lifters, jets, tensioners, etc., all dictate how much pressure and volume the engine will receive from the oiling system. If these bearing surfaces start to wear out (metal being extracted from the surfaces due to rubbing, or metal-to-metal-contact hammering and compressing the bearing surfaces), the pathway the oil must take is larger, and therefore, more oil volume flows, and that results in lower oil pressure. So it�s the wearing out of an engine that causes lower oil pressure (higher oil volume) over time, assuming oil weight has remain unchanged. That�s why older, worn engines - or rebuilt high performance engines - might benefit from higher weight oil, because it�s one small way to gain pressure. In the case of a high performance engine rebuild, the engine builder might have simply ended up with higher tolerances. But it doesn�t move the needle that much, and taken to the extreme (a 60w oil) might actually cause problems with VarioCam or other components. Especially if only one component of the engine is worn - such as bearings - heavier oil could accelerate an engine rebuild/damage because other engine components are getting started for oil volume (its all leaking out of a bad bearing). This is why Porsche doesn�t recommend too thin or too thick oil weight. If you have an older, loose engine, running higher oil weight will only buy you a certain amount of time and only a limited amount of pressure. The engine damage is done (any engine that�s ever been started more than zero times) and cannot be reversed. It�s not practical to just replace engine bearings, although several other engines are designed like this. A lower-end bearing swap on many older big rig engines is no problem at all and could take just a couple hours. But the M96 is not so easy to do this. The labor required would be high enough to warrant a rebuild. The reason why you might have much higher oil pressure after having the tensioners replaced is because oil was leaking out of your old tensioners - a loose engine indeed - and robbing the rest of your engine from good pressure. It�s better to bypass unneeded oil volume at the pump than pushing it up into the engine only to be wasted on it leaking out of a loose part. All of the above assumes street engines. The moment we start talking about a race track, and/or 250F oil temps or above in the twisties, it is well known that the M96 engine oiling system in not sufficient. Many people track their stock cars without trouble, but many have issues, some leading to wearing out faster, and some catastrophic engine failures due to a spun bearing, etc. If you are having oiling issues, then something is broken, something is wrong, and it should be looked into. But if you try to lower your oil pressure at this point, you�d be changing the engine design. If you did try, you�d either starve your engine of precious pressure needed at critical areas, or you would have to devise a way to reduce the volume, which could cause temperature issues if not enough volume is there to sufficiently cool the engine.

Nice write up Mike. Nothing new for me and I agree with most stuff so I will focus on the stuff which I don't agree/want to comment on. Do you have any reference where this is written/stated? Because I can't find that in the manual(I'm not the best at searching, maybe I just missed it?)....or anywhere else from a trustworthy source. Number 3, what is the right oil? According to me(and the manual I guess) you gauge the correct oil weight by checking the oil pressure according to the manual. If you'r not within, approximately, 3.5bar at 5k rpm, you have too high/low oil pressure. These failures can be explained by too high pressure causing bearing heat up which leads to accelerated wear and then failure. Just bluntly using thicker oil(and brand new at that) because you're doing a track day may not be a good idea. Check the oil pressure on the Cayman race car I linked to, less than 4bar at full speed. Plain bearings need a certain pressure but not a lot, more critically they do need flow for cooling. If you are seeing the 3.5bar at 5k you have well enough pressure, at half that you'r pushing it. More flow thru the bearings(and engine in general) is a good thing. Higher pressure gives less flow, lower pressure gives more flow...everything else equal. I'm pretty certain I will not do any damage what so ever as long as I have the stated pressure. I agree that I stopped a 'leak' by changing to fresh tensioners. They are updated revisions so maybe they are even tighter than the originals? Just speculating. Or, since my pressure is so high I'm thinking my engine has very small clearances inside and as such I should be running a thinner oil to get better cooling etc. I'm running Motul X-cess 5w40 right now with 2000km on it. For being a 40wt it's rather in the middle of the 40wt range viscosity. I've already decided to first change back to M1 0w40 since this is rather thin for being a 40wt. Take it from there.

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5 bar at high rpm is what most healthy stock 996 engines produce. Just ask around, ask the experts, etc. Few are producing 3.5 bar at 5,000, and those that are have had to rebuild or have had other issues. Mostly those issue are flickering oil lights at idle when hot. If you think 3.5 bar is a target, then what 20w or 30w oil (that Porsche does not recommend) will you be putting in your engine? And what will your hot idle oil pressure be? I�m guessing it could be quite low, possibly 1 bar or less. You say you are going to use Mobil1 0-40, but exactly how much oil pressure will that give you compared to another oil? I bet you will not be able to get to your target without invalidating the oil type and brand. No, bearings aren�t burning up because of too high oil pressure. It�s the opposite: temperature is either too high in that area (resulting in the oil losing its ability to protect with extremely low viscosity), or the oil pump has driven air into the oil stream (either cavitation or aeration). Finally, your engine doesn�t have too tight clearances. It operating just fine. It was in trouble before, and now it�s fine. If you really think you have too high oil pressure, then put a gauge on it and see what the peak reads. I doubt you will see much more than 70-80psi at 7,000 RPM, which is probably fine. I�ve never once read or heard of an M96 engine producing too high oil pressure, despite the fact that the oil pressure gauge is pegged at cold start and at high rpm for many cars.

You know, with thinner oil you have better cooling...and less cavitation/aeration....and, it's mainly not the viscosity that protects your engine. Your working on yesteryears fact, get in the game. This winter I asked 'Mr.Motul' on this forum about this exact question regarding viscosity and protection. There is no strong correlation, it's what's inside the oil that matters. Idle oil pressure will be correct if you follow the 3.5bar at 5k, otherwise they would not say that it's OK. The builder and constructor of the engine put in the manual that it should be approx 3.5bar at 5k. I think I trust that much more than the experts on this site. The car is 20years old and in the manual it states that oil have to fullfill API SH/SJ or ILSAC GF 1. A40 was not invented when they designed this engine, it came later. There are plenty to choose from in the 30-50wt range.

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Incorrect. It says �at least� 3.5 bar. What�s next, you are going to try to attain a minimum wage, Lol?

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Really?

OMG! This is exhausting.....and worthless....

It's a discussion forum, we discuss things. If you want something worthless you can tune in to TV and watch grown up men, very seriously, chase a ball.

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See here. Not the first time a manual has different guidance.

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I agree - I regret even contributing, since post #2 was 100% dead on. I wanted to save a poor soul from damaging their engine by trying to do god knows what, but I guess they are on a mission.

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Thanks for posting what's written in your manual, that is interesting. But, that manual is from a 997, not a 996....do you know that? The bypass valve was updated in the 997, making high pressure less of an issue since it doesn't bypass as easily, causing less aeration but increasing the risk of cavitation....if you think cavitation is an issues with these pumps. Your profile picture shows a 996, if you are unsure which model you have.... 997 came later. I hope you get a correct manual before you damage your car.

[QUOTE=Mike Murphy;16903365] 5 bar at high rpm is what most healthy stock 996 engines produce. [ /QUOTE] That's what mine does and I'm ok with that.

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Is your engine stock? I think I read you are running an oversize bespoke build, right?

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My mistake, I had a digital copy of manuals and this was labeled incorrectly. Still, you are really intent on doing something to lower your oil pressure, so go for it!

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You do notice I underlined "healthy" and not "stock"... I don't even want to mention what oil I use as it would blow some minds here.

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The bypass valve for our 996 engines was updated as well. Check it out. And you should update your engine with an LN Engineering spin on oil filter adapter so you can run a spin on oil filter that does not have a bypass valve. Stock canister has a bypass built in and it can get weak with age.

An appeal to the manual is pointless without it being the original German language manual. I recommend since OP is adamant he go ahead and fill his car with 5w-20.

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The original canister including filter cost around 25 USD....you can just go ahead a change it every time if you worry about the bypass valve. I much prefer the original since the oil filter sits so close to the road. If something snags/hits the spin-on filter (like a cargo securing strap or rock) you risk ruining your engine case and not just the 25 usd plastic canister. I assume from reading this thread that most of the responders spend their time in 6th gear doing 60mph on the freeway. Never revving over 5k in fear of the IMSB exploding. Then, it doesn't matter, I fully agree. When you start driving the car fast, like a sports car and on track, this stuff matters to keep the engine from breaking down. I just realise I'm discussing with the wrong people.

Yes, there is no one on here with any "racing" experience..at all. Yes, we all drive in 6th gear at 60 mph on the freeway. Please get in touch with Jake Raby and Charles Navarro in the future with your question(s). Thanks. Oh, and do some research at BobsTheOilGuy.com I can share with you some nice videos of my 996 on the Daytona International Speedway track

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You would actually be more likely to suffer IMS bearing failure if you ran at 60mph in 6th gear frequently.... You asked a question, didn't like the answer you got, then proceeded to argue with the people who answered your question. You don't need use for this. Just go ahead and put some Ford 5w-20 oil in it, it's your car, just please disclose to the next owner that you were sure to take extra steps to keep the oil pressure low.