High oil temp?

[Bruce]

From the other day at Dunnville Autodrome near the end of the day when I was more comfortable with the track and that I was able to push a bit harder, I was noticing that the oil temp was a bit on the high side after some hard corners. According to my RSM-G, I was pulling a max of 1.25G and after 10 laps or so when I went through few hard corners, my oil temp would rise to about 120 - 125 degrees Celsuis. Once I was back onto the long straights, it would slowly drop down to 110C. I had always learnt to start being cautious when the oil temp goes beyond 120C. As for the oil pressure, it never seemed to drop below 1.5kPa (~21 PSI).

I'm currently running with a HKS oil cooler, a Mugen baffled oil pan as well as using Liqui-Moly 10W60 synthetic oil. I checked my oil afterwards and it was fine without any hint of oil burning. I'm confused in what would be causing this. Perhaps my baffled oil pan isn't suffice? If so, then why was the oil temp still remained normal? Could it be that I was just too paranoid and shouldn't worry until the oil temp gets above 130C?

Any suggestion is appreciated.

Thanks.
Bruce L.

[Slowpoke]

Damn... I have to pound on my car for a long period to get the oil temp that high and that's only with a stock sandwich cooler at the filter. (Different world... boost instead of high compression, I know, but usually turbos can create incredible heat.)

The first thing that occurs to me was... were you using a high viscosity, high quality synthetic? Yup! That doesn't appear to be the problem...

The second thing that occurs to me would be asking, how much air flow is actually going through your oil cooler? If it's sitting in front of your A/C condenser that's damaged by stone chips, and your stock rad, you may not actually be seeing much flow.

Is a RSM-G an OBD-II type meter? Where is the sensor located? Oil pan? Oil galleries?

[MilesM]

That's way too high. Bruce runs a turbo btw. At the end of the day at the track oil loses its ability to disapate heat so it's normal for it to rise a little, but not to 130. A little warmer and the oil will lose all its viscosity. Start with a larger oil cooler. They're not that expensive. Retrofitting a truck tranny cooler is also something I've heard of being done. Another cheap fix is to direct all the air going through the front bumper better. Don't let any air go above, below or to the side of the rad. All air must go through it. Air goes through the path of least resistance. If you give it the option to go under or around an object it will. Also, turn down the boost for track driving. Will save you lots of troubles in the long run.

[mxqisit]

How good is your water cooling system? Do you have an upgraded rad? Stronger water pump? Running 90% water?

Improve your water cooling, and your oil temps will drop too.

[Bruce]

Thanks for everyone's suggestions and comments.

The second thing that occurs to me would be asking, how much air flow is actually going through your oil cooler? If it's sitting in front of your A/C condenser that's damaged by stone chips, and your stock rad, you may not actually be seeing much flow.

Is a RSM-G an OBD-II type meter? Where is the sensor located? Oil pan? Oil galleries?

The oil cooler is actually between the intercooler and the radiator. Perhaps, the IC might be taking alot of the air that's flowing in.

The RSM-G isn't an OBD-type meter. It just reads Speed, RPM, etc. from the ECU while the g-forces are from the G-sensor which is mounted at the center of my car just underneath the center console. Oil pan is from Mugen which is a baffled version of the OEM.

That's way too high. Bruce runs a turbo btw. At the end of the day at the track oil loses its ability to disapate heat so it's normal for it to rise a little, but not to 130. A little warmer and the oil will lose all its viscosity. Start with a larger oil cooler. They're not that expensive. Retrofitting a truck tranny cooler is also something I've heard of being done. Another cheap fix is to direct all the air going through the front bumper better. Don't let any air go above, below or to the side of the rad. All air must go through it. Air goes through the path of least resistance. If you give it the option to go under or around an object it will. Also, turn down the boost for track driving. Will save you lots of troubles in the long run

As for the high oil temp, it will only happen during high-g corners while it's around 105-110C on the rest of the turns and straights. Would a Moroso oil pan with the extra capability help in this case?

I will check on a larger oil cooler as well as a tranny cooler. As for the boost, I was shifting around 5000-6000 rpm most of the time, so I don't think it was on full for that long duration.

How good is your water cooling system? Do you have an upgraded rad? Stronger water pump? Running 90% water?

Improve your water cooling, and your oil temps will drop too.

My water cooling system is fine. It was always around 100-110C. Yup, I'm running a larger aluminum rad from C&R Racing. Hmm...the water pump is stock though. As for coolant, I'm running 50/50. Perhaps, I should consider changing the last two.

Just curious, since my water temp is good, will doing this be putting my water out of the optimal range?


Great suggestions. Thanks so much.

[mxqisit]

My water cooling system is fine. It was always around 100-110C. Yup, I'm running a larger aluminum rad from C&R Racing. Hmm...the water pump is stock though. As for coolant, I'm running 50/50. Perhaps, I should consider changing the last two.

Just curious, since my water temp is good, will doing this be putting my water out of the optimal range?


Great suggestions. Thanks so much.

100-110*C? That's really high for water temp, IMHO. I'd try going to 80/20 water at least. And don't forget your fans, they can help a LOT to get air through all of your radiators.

[MilesM]

We run 75C or 170F. It's usually at the thermostat crossover. Another trick we've done is drill a hole in our stock thermostat. Allows more flow through it - the downside is it takes longer to get to temperature. If you winter drive, you may never get heat into your car.

[MilesM]

Oh, another thing to check is the wiring of the fans. I ran my FAL fans using the stock wiring, but it didn't seem to be getting enough power, so rewired it using a relay to get the full 12-14V and now - holy cow - thing really blows! :) Huge improvement and all that's needed is a couple bucks worth of wiring and a relay.

[Bruce]

Thanks Miles. Those are very great suggestions.

[1999_ITR]

Miles 170f is actually too low man. You should reach 180-200F. Running that cool can actually cause alot of issues as well.

I run a Visteon(C&R) full aluminum Radiator with Mugen Thermostat and Mugen Fan Switch and my temps on the track are about 190F when I datalogg.

[Slowpoke]

Ah! Well, turbos... now I'm more comfortable yapping about oil temps...

My water cooling system is fine. It was always around 100-110C.

That is rather high! Frank Sprongl used to tell me that he used to run those coolant temps on the Audi because it made the best power on that engine, but our Subaru thermostats maintain 90C / 194F on the return line. Both fans kick on at 94C. "Ideal" temperature for a motor really depends on what tolerances it's built with. I would check if you can find a little bit cooler Thermostat to maintain 90C ish. Do you know what your current one opens at? Is it a relatively new thermostat? (you can put one in a pot on the stove with a thermometer to test.)

What compression and boost pressure do you run?

I went FMIC last year instead of my TMIC and had trouble with coolant overheating immediately to 100C-104C, that cascaded to my oil temp. I tried upgrading to a Koyo racing rad with 3 rows... still have the same problem. An extra row doesn't do any good with too many coolers stacked out front blocking air flow. I added extra hood venting up top. (I'm still running full factory AC with a stone-dented condenser.) So I'm going to change out the AC Condenser for an undamaged brand new one and hope that does the job.

I think that your issue is likely the same... too much stack out front blocking airflow. You can stick foam in any gaps between the air dam and the radiator edges to prevent air from going around the heat exchangers, and add a splitter to help increase air through the stacked coolers.

I would try to avoid the drilled hole through the thermostat if possible... as you may have realized (depending on your boost pressure and cylinder wall clearances), hit the throttle hard before your turbo motor is warmed up and a huge amount of oil disappears in a white cloud out the back of the car as it blows past the rings. (Then again I run 26psi boost with 0.0045" clearances and ~8.7 compression ratio.)

[Bruce]

That is rather high! Frank Sprongl used to tell me that he used to run those coolant temps on the Audi because it made the best power on that engine, but our Subaru thermostats maintain 90C / 194F on the return line. Both fans kick on at 94C. "Ideal" temperature for a motor really depends on what tolerances it's built with. I would check if you can find a little bit cooler Thermostat to maintain 90C ish. Do you know what your current one opens at? Is it a relatively new thermostat? (you can put one in a pot on the stove with a thermometer to test.)

I'm running the Mugen one. I don't remember when it opens but lower than the stock 88C. Both thermostat and switch are few years old. Perhaps, they're going out.


What compression and boost pressure do you run?

I'm at 9.4:1 compression and running 10psi on a T3/TO4E 57 Trim.


I went FMIC last year instead of my TMIC and had trouble with coolant overheating immediately to 100C-104C, that cascaded to my oil temp. I tried upgrading to a Koyo racing rad with 3 rows... still have the same problem. An extra row doesn't do any good with too many coolers stacked out front blocking air flow. I added extra hood venting up top. (I'm still running full factory AC with a stone-dented condenser.) So I'm going to change out the AC Condenser for an undamaged brand new one and hope that does the job.

I think that your issue is likely the same... too much stack out front blocking airflow. You can stick foam in any gaps between the air dam and the radiator edges to prevent air from going around the heat exchangers, and add a splitter to help increase air through the stacked coolers.

I would try to avoid the drilled hole through the thermostat if possible... as you may have realized (depending on your boost pressure and cylinder wall clearances), hit the throttle hard before your turbo motor is warmed up and a huge amount of oil disappears in a white cloud out the back of the car as it blows past the rings. (Then again I run 26psi boost with 0.0045" clearances and ~8.7 compression ratio.)


Thanks. I will try that.

Miles 170f is actually too low man. You should reach 180-200F. Running that cool can actually cause alot of issues as well.

I run a Visteon(C&R) full aluminum Radiator with Mugen Thermostat and Mugen Fan Switch and my temps on the track are about 190F when I datalogg.

Hey Mark,

190F is about 88C. I'm using the same rad and thermostat, but spoon fan switch which is basically same as Mugen. I guess I'm a bit on the high side being around 100C and at the end of 20 mins session, it'll be close to 110C.

Are you running straight water or mixture of coolant/water. If latter, what's your percentage of mixture?

Thanks.

Bruce L.

[MilesM]

Our temps are really low at idle. 165F tops. Race temp it hits as much as 210 but cool down it falls again to 170ish. Stock Thermo is 180F, Mugen is 170, Crappy tire replacement thermos are 175. We have no overheating issues with the big rad, water/coolant ratio, and 2L oil cooler. The hole in the thermo was something Paul did and seems to work for us keeping temps down in race conditions. Just in the pits and starting cold in the morning it takes forever to get up to temp before we can really beat on it. What issues are you refering to? Mugen thermos keep cars running at 170.

[Slowpoke]

I'm running the Mugen one. I don't remember when it opens but lower than the stock 88C. Both thermostat and switch are few years old. Perhaps, they're going out.

Is your car a race car only or does it do street duty as well?

My 4 year old 70,000km OE thermostat only opened to about 2/3 the distance of a brand new thermostat in the heating water test. If you order another Mugen ... do the boiling water test versus your current thermostat. Your old might still be fine but you really need a good new one to compare it to. Keep the old one as a spare if it's still good.

Another thing... to be scientific about it... you might want to compare the Mugen to a stock thermostat. Opening temperature is one thing, but once you're up to and above temperature, it's the size of the opening that decides how much cooling you get. It's theoretically possible that a "performance" thermostat might have a big heavy spring that blocks more coolant flow than a stock thermostat.

... but I'd still guess that it's not enough airflow through the stacked heat exchangers, and that there's nothing designed wrong with the Mugen.

(p.s.: Don't mention to my wife that I used her pots to test thermostats while she was at work.)

[Bruce]

Actually, it's for both track and street. I used to have it track only few years ago, but I've changed it back to street format now.

As for the thermostat, I think I'm going to change it regardless like you said since the current one being that old, it probably lost its effectiveness. Being on street is not an issue, but I guess on track, every bit counts.

[1999_ITR]

Our temps are really low at idle. 165F tops. Race temp it hits as much as 210 but cool down it falls again to 170ish. Stock Thermo is 180F, Mugen is 170, Crappy tire replacement thermos are 175. We have no overheating issues with the big rad, water/coolant ratio, and 2L oil cooler. The hole in the thermo was something Paul did and seems to work for us keeping temps down in race conditions. Just in the pits and starting cold in the morning it takes forever to get up to temp before we can really beat on it. What issues are you refering to? Mugen thermos keep cars running at 170.


Bruce,

I'm running mostly distilled water and water wetter with a little coolant mixed in.

Miles,

If you run too cold and never get up to operating temp you will run VERY rich which can wash out cylinder walls which will eventully cause an oil burning problem. Your temps sound fine though. I thought you meant that you got to 170 at the hottest.

[Bruce]

Thanks Mark. I might just run the same now that the car is stored for the winter. Thanks.