Oil pressure track data

[ayau]

Here's a graph showing oil pressure vs RPM while on track. Car doesn't have oil temp data, so this is the best we can do. This is on factory 0w20 oil on E30 tune. No oil cooler. Pressures should be higher IMO, so I'll try 5w30 next time and re-log.

49 psi @ 4000 RPM
48 psi @ 5000 RPM
46 psi @ 6000 RPM
43.5 psi @ 6500 RPM

Per factory manual, oil pressure specification is:

 

[FlexRex]

Was this yours? Ballpark temps? Or no data at all? Surprised pressures go down w higher rpms.

 

[ayau]

Was this yours? Ballpark temps? Or no data at all? Surprised pressures go down w higher rpms.

Yea this was my car. About 78-80F ambient if I recall correctly. No oil temp data. Oil temps are probably too hot, so oil pressure drops as RPMs go up is my guess.

I don't this is surprising for a production street car without a factory oil cooler.

 

[FlexRex]

I don’t either and i suspect same about temps which is why i asked. Can you track oil next time or no? If not, can you track oil press at beginning of session then stop and start another log later when warmed up. To confirm drop due to temps and document amount of it, easier to look at two sets to discern a pattern than all in one id think.

I would run 0w40 personally, especially tuned on a track. I do in my car and i dont even track it, not sure what oem for wrx is but i suspect 0w20 or 0w30. Never monitored my pressures though, not possible thru Cobb AP and thats all i have.

Higher grade oil will also tend to run a bit cooler so maybe you can find a happy medium between a grade and oil temp without needing a cooler.

Thanks for posting.

 

[ayau]

I don’t either and i suspect same about temps which is why i asked. Can you track oil next time or no? If not, can you track oil press at beginning of session then stop and start another log later when warmed up. To confirm drop due to temps and document amount of it, easier to look at two sets to discern a pattern than all in one id think.

I would run 0w40 personally, especially tuned on a track. I do in my car and i dont even track it, not sure what oem for wrx is but i suspect 0w20 or 0w30. Never monitored my pressures though, not possible thru Cobb AP and thats all i have.

Higher grade oil will also tend to run a bit cooler so maybe you can find a happy medium between a grade and oil temp without needing a cooler.

Thanks for posting.

It's not possible to log oil temp data. There isn't a sensor (supposedly). Closest data point would be engine coolant temp (ECT) as shown in the second graph. It looks like there's a pretty strong correlation. As ECT rises, oil pressure drops.

I believe running one grade thicker will help, so using 5w30 is completely fine for track and daily driving. However, once you go too thick, you'll end up creating even more heat and the engine already has heating issues after a certain point. I didn't experience it myself though. I'm guessing the oil pressures may look pretty scary on an overheated car.

This is just one data point, so it doesn't really mean your engine will fail below a certain oil pressure. It certaintly doesn't hurt to try to maintain OEM specified oil pressures at al times. I'm not sure if anyone has torn apart the stock engine to really examine the oiling system. Just thought I'd share this data. Maybe someone that's an expert in this field can chime in.

 

[elmoTK]

Here's a graph showing oil pressure vs RPM while on track. Car doesn't have oil temp data, so this is the best we can do. This is on factory 0w20 oil on E30 tune. No oil cooler. Pressures should be higher IMO, so I'll try 5w30 next time and re-log.

49 psi @ 4000 RPM
48 psi @ 5000 RPM
46 psi @ 6000 RPM
43.5 psi @ 6500 RPM

Per factory manual, oil pressure specification is:

View attachment 240686

Double check what you read applies to what you are working on. My first hint those aren't the correct specs is the oil capacity. Those specs are for the K20C2. Here are the specs for the Type R.

 

[FlexRex]

No it wont fail until it fails though.. what i mean is less pressure is less lubrication between bearings and crank/rods. So it wont fail but id certainly like higher pressures. From my readings one wants 10psi per 1k rpms at least especially in a tuned performance car. Just what i read though.

0w40 oil should pour same as 0w20 oil at cool temps but it will “pour” (for lack of better term) harder at high temps, say 230f. If that makes sense, simplistic explanation.

I never heard anyone overheating due to too heave oil use unless they used straight heavy grade oil. Not an expert either but did a plenty of reading.

 

[ayau]

Double check what you read applies to what you are working on. My first hint those aren't the correct specs is the oil capacity. Those specs are for the K20C2. Here are the specs for the Type R.

Wow, my bad. Completely skimmed over that detail. I'll update my original post.

 

[ayau]

No it wont fail until it fails though.. what i mean is less pressure is less lubrication between bearings and crank/rods. So it wont fail but id certainly like higher pressures. From my readings one wants 10psi per 1k rpms at least especially in a tuned performance car. Just what i read though.

0w40 oil should pour same as 0w20 oil at cool temps but it will “pour” (for lack of better term) harder at high temps, say 230f. If that makes sense, simplistic explanation.

I never heard anyone overheating due to too heave oil use unless they used straight heavy grade oil. Not an expert either but did a plenty of reading.

Yeah, I see what you're saying. It's probably fine running 0w40 at the track since your oil temps will be hotter than street driving. The higher temps may reduce the viscosity enough to put it in the engine's oil pressure "sweet spot", but you may run 10-30F (made up numbers) hotter than 0w20.

On the street, 0w40 may be too thick and may potentially provide insufficient lubrication, so you'd want to change it back to 0w20 or something thinner. In fact, the ZL1 1LE owner's manual recommends changing to 15w50 at the track and swapping back to 0w40 in the streets.

The solution is to keep the oil temps in check by running an oil cooler, but that has its drawbacks as well. In general, I wouldn't run an aftermarket oil cooler if the car sees more street miles than track miles. That's just IMO and my risk tolerance.

 

[ayau]

Here's a 4th gear pull. You can see the oil pressure is within OEM spec at normal oil temps. ECT is from 172-188F.

I'm curious to see the oil pressures with 5w30 at normal oil temps. Will update this thread after I do my next oil change. Hopefully in the next week or so.

 

[FlexRex]

0w40 will run Colder not hotter than 0w20. Counterintuitive at first thought.

Id consider installing an aftermarket temp gauge since you track it. Hard to select best oil based on pressure by guessing temps.

 

[ayau]

0w40 will run Colder not hotter than 0w20. Counterintuitive at first thought.

Id consider installing an aftermarket temp gauge since you track it. Hard to select best oil based on pressure by guessing temps.

Want to share how running thicker oil at operating temp will result in cooler engine temps?

https://blog.amsoil.com/what-happens-if-i-use-the-wrong-weight-viscosity-of-oil/

 

[FlexRex]

Sure. I first observed mine switching from oem fill to 0w40 mobil 1 fs. Takes longer to reach operating temp and its lower. Heres why

First is a guy eloquently but shortly explaining it. Second is a guy whos confused a lil by his assumptions vs observations.

Hope that helps. Id fill 0w40 personally and call it day. Good for everyday (0w) and perhaps enough for track too (40). You may need 0w50.. we dont know temps and theres a sweet spot you want. Id strongly consider getting a temp gauge if you are set on tracking. Also, if youre set on 0w30 oil there is an excellent Renewable Lubricant oil I can’t highly recommend enough, based on what i read. Best out there really.

 

[Gansan]

For the second guy, he is comparing a stock engine with a supercharged one with a different tune. We have no idea if the Lingenfelter package was running a bit richer and thus cooler. Lingenfelter also sells oil coolers and we would want to confirm if his package included one. It seems unscientific to compare the two cases without more info. A much better example would be if that guy put oem 5w30 into his Lingenfelter and compared temps under the same conditions.

 

[FlexRex]

For the second guy, he is comparing a stock engine with a supercharged one with a different tune. We have no idea if the Lingenfelter package was running a bit richer and thus cooler. Lingenfelter also sells oil coolers and we would want to confirm if his package included one. It seems unscientific to compare the two cases without more info. A much better example would be if that guy put oem 5w30 into his Lingenfelter and compared temps under the same conditions.

I DID THAT.

I observed my oem fill reach 235-240 in street driving while my 0w40 reaches 235 only on hwy at 90mph sustained speed in 120f ambient (AZ). In street driving its 215-220 (whereas it used to be 235-240). So 15f less going from oem (w20 or w30) to w40.

It’s physics. Heat absorbtion required to raise temp by one deg, thicker oil needs more heat absorbed to raise the temp than does thinner oil. Try it yourself.

Oil is such a big topic yet misunderstood. Kinda like covid19.. not to side track but assume what the mortality rate is then divide deaths by usa population (for mortality chance) and then by confirmed cases (for mortality rate). Try the exercise to see how much we assume and how much we actually know.

Having said all of this about oil, just cuz oil will be perfect for track operating temps/press does not mean it will be perfect for street operating temps/press. But you gotta give something (assuming using same oil) and id rather give on the street.

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