Oil temperature hotter after once heated?

filip00 · 05-26-2022, 11:12 AM

I tried to search this issue but haven't found it.

At normal driving my oil temp is always around solid 90°C (194 F). I went for a track day where I had 3 runs in total, with not more than 5mins of faster driving, where my oil temp always reached a max of 125°C (260 F). Each time I left the car to cool down and all is well.
However, now after this I noticed that my normal driving temp is now always about 100°C. Does this mean that I've "burnt" the oil? I.e. is the cooling capacity of the oil destroyed?
My gallery gaskets are aftermarket, changed last year, oil color seems perfectly fine, no loss of oil, engine working perfectly, all good and no symptoms. It's just that normal oil temperature is now higher.

This EXACT same thing happened last year when I also went for a run on the track, where I wasn't pushing the car a lot, and I didn't exceed oil temp into some crazy numbers. Since then I changed the oil and it was fine, until now, again when I reached higher temps.t

I'm just worried why the sudden difference in running temperature, is this normal, is there anything I should check? Did I break down the oil?

For reference, It's Mobil 5w30.

Thanks!

ZoomZ · 05-26-2022, 12:27 PM

Check the temp sensor against a known value. The FSM may have those numbers.

SouthArk370Z · 05-27-2022, 05:23 AM

My guess is that the oil has changed a little bit, from use, and is not transferring heat quite as well. Or it could be the filter has clogged up and is reducing flow through the system.

First thing I would do is change oil and filter. If that fixes the problem, I'd quit worrying about it. YMMV

If changing oil/filter doesn't work, I have no idea what the problem might be.

filip00 · 05-27-2022, 09:51 AM

Quote:

Originally Posted by SouthArk370Z

My guess is that the oil has changed a little bit, from use, and is not transferring heat quite as well. Or it could be the filter has clogged up and is reducing flow through the system.

First thing I would do is change oil and filter. If that fixes the problem, I'd quit worrying about it. YMMV

If changing oil/filter doesn't work, I have no idea what the problem might be.

Yes, that's what resolved the same exact symptoms last year. It was also after a track day, and also normal running temp was higher, and when I changed oil and filter, it was all back to normal again.

I suspect it's the same now, but what that tells me is that probably the oil isn't that good, or I managed to kinda destroy it.

Thanks!

THE BULL · 05-27-2022, 02:23 PM

Any oil cooler?

Technically after a spirited run oil should start seeing some fuel dilution.
An oil change to the same weight will confirm this.

Are you tuned?

Excessive rich AFRs will dump fuel into the crankcase and dilute the oil. Diluted oil will stay warmer.

Are you running a circulated catch can or stock PCV system?
If your PCV is open to atmosphere then vapors will hang in the crankcase exacerbating the problem.

A circulated system will be pulling some of those vapors out of the crank case.

Start with the changing of the oil along with putting this oil through the ringer and observe operating coolant temp oil temperatures.

You should start seeing higher oil temps over time.

filip00 · 05-28-2022, 05:58 AM

I don't have an oil cooler yet, and nor did I tune the car. It's all stock.
I'll change the oil soon and follow up on this. Thanks guys!

THE BULL · 05-30-2022, 03:20 PM

Quote:

Originally Posted by filip00

I don't have an oil cooler yet, and nor did I tune the car. It's all stock.
I'll change the oil soon and follow up on this. Thanks guys!

Nothing you do will get rid of this unfortunately.

If you own anything with a VQ and drive it like it's meant to the oil temp WILL go up. Start looking for an oil cooler.

Rusty · 05-30-2022, 04:22 PM

If you are tracking the car hard. Get a 34 row oil cooler.

05-26-2022, 11:12 AM	#1 (permalink)
filip00 Track Member Join Date: May 2021 Location: slovenia Posts: 573 Drives: 370z pack Rep Power: 125427	Oil temperature hotter after once heated? I tried to search this issue but haven't found it. At normal driving my oil temp is always around solid 90°C (194 F). I went for a track day where I had 3 runs in total, with not more than 5mins of faster driving, where my oil temp always reached a max of 125°C (260 F). Each time I left the car to cool down and all is well. However, now after this I noticed that my normal driving temp is now always about 100°C. Does this mean that I've "burnt" the oil? I.e. is the cooling capacity of the oil destroyed? My gallery gaskets are aftermarket, changed last year, oil color seems perfectly fine, no loss of oil, engine working perfectly, all good and no symptoms. It's just that normal oil temperature is now higher. This EXACT same thing happened last year when I also went for a run on the track, where I wasn't pushing the car a lot, and I didn't exceed oil temp into some crazy numbers. Since then I changed the oil and it was fine, until now, again when I reached higher temps.t I'm just worried why the sudden difference in running temperature, is this normal, is there anything I should check? Did I break down the oil? For reference, It's Mobil 5w30. Thanks!

05-26-2022, 12:27 PM	#2 (permalink)
ZoomZ Track Member Join Date: Jan 2017 Location: Vancouver, BC Posts: 781 Drives: 17' 370Z Nismo Rep Power: 40656	Check the temp sensor against a known value. The FSM may have those numbers. cv129 and stansens like this.

05-27-2022, 05:23 AM	#3 (permalink)
SouthArk370Z Premium Member Join Date: Nov 2010 Location: South Arkansas Posts: 8,435 Drives: 2014 Challenger Rep Power: 324198	My *guess* is that the oil has changed a little bit, from use, and is not transferring heat quite as well. Or it could be the filter has clogged up and is reducing flow through the system. First thing I would do is change oil and filter. If that fixes the problem, I'd quit worrying about it. YMMV If changing oil/filter doesn't work, I have no idea what the problem might be. JARblue, cv129 and filip00 like this. __________________ Steering Lock Links - Search The370Z Bookmarklet - FSM @ NICOclub Mankind has progressed past the need for war but we haven't evolved that far. - NachoMahma

05-30-2022, 04:22 PM	#8 (permalink)
Rusty Ronin Samurai - Assassin Join Date: Dec 2011 Location: Fayettenam,Pennsyltucky Age: 69 Posts: 35,383 Drives: 2011 Nismo GM 6M Rep Power: 2684438	If you are tracking the car hard. Get a 34 row oil cooler. __________________ 浪人 - 殺し屋 "The Difficult Anytime, The Impossible By Appointment Only" http://www.the370z.com/members-370z-...o-journal.html

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05-27-2022, 02:23 PM	#5 (permalink)
THE BULL Base Member Join Date: Apr 2021 Location: Florida Posts: 217 Drives: G37S Rep Power: 26849	Any oil cooler? Technically after a spirited run oil should start seeing some fuel dilution. An oil change to the same weight will confirm this. Are you tuned? Excessive rich AFRs will dump fuel into the crankcase and dilute the oil. Diluted oil will stay warmer. Are you running a circulated catch can or stock PCV system? If your PCV is open to atmosphere then vapors will hang in the crankcase exacerbating the problem. A circulated system will be pulling some of those vapors out of the crank case. Start with the changing of the oil along with putting this oil through the ringer and observe operating coolant temp oil temperatures. You should start seeing higher oil temps over time.

05-28-2022, 05:58 AM	#6 (permalink)
filip00 Track Member Join Date: May 2021 Location: slovenia Posts: 573 Drives: 370z pack Rep Power: 125427	I don't have an oil cooler yet, and nor did I tune the car. It's all stock. I'll change the oil soon and follow up on this. Thanks guys!