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Last weekend we had mid-70s and sunny. Oil temps were hitting 240, and creeping on 260 if I was nose to tail for a few laps. Water temps (on stock guage) were fine (below mid point). Any suggestions?
The month before when it was 50s, temps didn’t really get over 220.
It is not uncommon to see those temperatures periodically in race conditions and not the end of the world.
There are a couple of assumptions here;
You are running a stock oil cooler and it is working. Correct?
The gauge is accurate?
It also matters where the temperature probe is reading the oil temperature. If it is at the bottom of the sump and away from the exhaust, that is fairly hot.
240 and 260 is pretty hot for conventional oil but once again, depending upon where the temp is taken, it may or may not be reason for concern. It relly depends on what the temperature is at rod bearings, cam bearings and followers, and piston ring seal area.
Synthetic oil can withstand the heat more effectively and may provide some peace of mind.
Don
Stock cooler (I assume its working)
Temps taken from a dist block installed where the stock light switch goes
M-1 15/50 oil
Back when I was more of a nutjob I would get obsessed with a different aspect of our cars every couple of months. One of obsessions was oil temp. Look around for some of those threads. At one point I had 4 oil temp sensors in the car, and I probably had 2 oil temp sensors for 18months.
Lessons learned.
Different places get different readings. Some oil temp sensor locations work pretty well and others suck. You can’t measure oil temp at the OEM OP port because it’s not in the oil flow. I have a theory that the lower half of the block, because it’s the only part not cooled by the water jacket, gets pretty darn hot. This would make the area of the OEM OP port quite hot. So even if you could get it into the flow there, the oil temp readings would be distorted by the heat.
The OEM oil cooler sucks. On it’s best day with optimal shrouding it’s good for 3-4deg. And few have it shrouded. It’s inefficeint because it’s small and it’s tilted down in a horiz air flow.
The two best ways to cool your oil are to have a really robust water cooling system that keeps your engine cool, and to allow lots of air flow to hit the oil pan. I don’t run an oil cooler at all and my oil is a helova lot cooler than it was back when I had the full OEM setup.
DEFINITELY NOT M1 OIL!!! No wear additives (zink) to protect against cam wear. Use a good racing only oil such as Valvoline, AmSoil, etc. which has extra zink to lubricate the cam/lifter interface.
I like to take oil temps form the oil pan. That way you get to see the oil temp coming off the bearings and that is really the only thing you need to know. I also use an 11" X 11" oil cooler in front of the double pass radiator I run. Summer temps (100+ track temps) I see 185 on the water and 225 on the oil. I feel safe with that. Chuck
In my old American Sedan I would watch the gauge peg at 280 and know it is up to operating temperature…
That doesn’t help does it?
Shit, my VR6 Corrado would see 311 on a hot day at Gman. Nothing like a big motor, in a little box, with a slit for a breathing hole!
I remember from 15 years ago when I had a Hot Rod subscription that they always insisted on 270 being optimum temp, of course they were usually talking about pushrod motors. I wish I could tell you what oil temps I ran at Autobahn but I put my oil temp bung in back of the pan and it interfered with the steering rack so I had to plug it. I know my accumulator never got warm but If I didn’t have pickup issues I wouldn’t have been cycling any oil through it anyway.
If you’re running a skid plate I think Ranger has some skid plate venting theories he might share. I will probably learn that I need a skid plate the hard way.
I’m convinced from my research that Red line racing is the best with Amsoil possibly equal. Anyway Bimmerworld sells red line so you can use that big contingency check on an oil change. I used resolute 20w50 racing for my brake in which is about 1.70 a quart at fleet farm. I’m not sure if it has the dreaded api certification or not, but it’s my oil of choice for worn out motors. Or since you already have a synthetic you can dump in a bottle of break in additive which is pure zinc and phosphorus.
IMO, if you are seeing oil temps in the 250 range, you have a problem. I saw my peak numbers during the Sunday race; water reached 170 and the oil temp (measured at the oil filter adapter) reached 214. Switching to a 71 C (160 F) thermostat might bring water and oil temps down a bit.
On another note, why such thick oil? I used to run VR1 20W50 (conventional) and had much higher oil temps. Redline or Valvoline 30wt racing synthetics are excellent options that likely protect better than the M1 50wt.
I agree that if you have a decent oil cooling system thinner oils will run cooler. This is because they shed heat better. But if your oil cooling system sucks, say for example the OEM oil cooler, it won’t make much difference.
Redline oils, like Brad Penn oil, have such terrific high temp shear #"s that I agree with Fish that Redline oil can be run a little light. That is to say, if you are now running an average xW50, you’ll get the high temp shear #'s out of a Redline xW40. All else being equal, lighter oils have lower high temp shear #'s. But some oils have such particularly good high temp shear #'s that you can drop a visc grade w/o lowering your high temp shear (HTHS)
I have 7-8qts of Redline 20W50 looking for a good home btw.
I don’t agree that cooler tstat will make your engine run cooler tho. An OEM 180deg tstat is fully open at 190deg. So if your coolant is 200deg on a hot day, then the 170deg tstat isn’t going to help any.
Now if your engine is 185deg at full hot with a 180deg tstat, then a 170deg tstat will make it run a little cooler.
I think that all this is irrelevant tho. The key point is that the OEM OP port is an unsuitable location to measure oil temp. Like Chuck my favorite place to measure oil temp is the pan. Weld a bung into the right side of the pan, just as low as you can safely put it. Then put the temp sensor in the bung.