Engine oil temps

[Steve.k]

What is general rule on engine oil temps? I like to stay under 200f. I’ve read some like it as high as 240+ but to me that seems high. On our heavy equipment we try to keep oil temps no higher than 200. Of course these engines see a lot of continuous load cycles.My dyno operator does not like to make pulls if temps hit 240. Shuts down and cools oil.

[dannobee]

Cup cars are what, over 300 degrees now? "Normal" has always been somewhere over 200 to get the water and crap boiled out. Less than that and the mocha shake sludge tends to form under the valve covers.

[Steve.k]

So they say. Although never seen the sludge on anything but diesels left to idle over cold winter nights to cold to shut off.

[peejay]

I like to see oil OVER 210 degrees, except on Mazda rotaries, where it seems like power output is in direct inverse relationship to oil temp due to the way the oil is used as the cooling system for the rotors, and hot rotors will kill VE.

Under 300 depending on what bearings it has, some bearing materials will start to bubble and flake when oil gets that hot.

"Oil be oil, mon." The temps are to keep the engine happy, not the oil. The oil is ultimately a consumable and should be tailored to what the engine needs, not the other way around.

[Steve.k]

Wow thats way warmer than I would have thought. I’ve been watching my diesel since this discussion with others and this truck sits around 190. However i’m not sure where they stuck heat probe.

[j-c-c]

So this question makes me wonder, underside piston oilers with the main purpose of cooling the piston, would seem to benefit from lower temp oil, sio why or maybe how common is it to use a separately plumbed off the main supply and then externally Air to oil cooled for the piston spray circuit? The vouln\me is not high I supect and the oil cooler would not be overly large if given adequate air flow. N

Not meaning to hijack, but is oil temp realted.

[midnightbluS10]

For passenger cars, normal operating temp is anything below 250 or 260* F. It's not considered overheating until that point.

[swampbuggy]

I believe the NASCAR engines run between 260-280 degrees oil temp. Mark H.

[RW TECH]

What is general rule on engine oil temps? I like to stay under 200f. I’ve read some like it as high as 240+ but to me that seems high. On our heavy equipment we try to keep oil temps no higher than 200. Of course these engines see a lot of continuous load cycles.My dyno operator does not like to make pulls if temps hit 240. Shuts down and cools oil.

Yellow warning limits are typically set to trigger at 260°F, and red shutdown limit is typically 280°F. This is in an OEM lab.

FWIW, back when dry sump pans were absolute crap it was not uncommon to see over 300°F oil temps in asphalt late models with 358 CID turning about 8200 RPM at the end of the chutes.

In one case, the oil was always straight 30-wt conventional Valvoline ashless, non-detergent oil. Their typical oil temp was ~320°F and there NEVER was a problem related to excessive heat in the oil.

[Kevin Johnson]

Be certain to consult with the lubricant engineer (tribologist):

... Tim Wusz mentioned that Unocal was testing for foaming with oils and one particular 10w30 would begin to do this in a test engine within a very narrow temperature window, say 255 F stop; 260 F foaming. ...

IIRC the context was a problem with patrol cars idling for extended periods. I also recall him saying that the OEM was unaware of the issue.

[CGT]

I like to see the oil at least get to water boiling point. Pulling vacuum on the crankcase changes that. Another plus for vacuum. Oil can get pretty shitty by not getting the oil hot enough under the right conditions...cool weather especially.

My dyno operator does not like to make pulls if temps hit 240

It would take some effort to get 240° oil temp making pulls on the dyno from what ive seen. Most stuff with modern ring packs are hard to get the oil hot in..on the dyno, especially at idle. It usually takes making a pull or 2 to get some heat in the oil. Once the oil is saturated it seems to want to stay around 200° roughly. At least on the stuff Ive messed with anyway.

[Kevin Johnson]

... it was not uncommon to see over 300°F oil temps in asphalt late models with 358 CID turning about 8200 RPM at the end of the chutes.

...

Temps of 300°F were reported to me in Honda D15 road race engines with poor oil control. I believe Mike Kojima also mentioned temps skyrocketing in Nissan SR engines if overfilled with oil.

[Kevin Johnson]

...
It would take some effort to get 240° oil temp making pulls on the dyno from what ive seen. Most stuff with modern ring packs are hard to get the oil hot in..on the dyno, especially at idle. It usually takes making a pull or 2 to get some heat in the oil. Once the oil is saturated it seems to want to stay around 200° roughly. At least on the stuff Ive messed with anyway.

Part of the issue with the D15 was the exhaust pipe routed under the shallow end of the pan thereby bathing it in heat. That might show up on a roller dyno. Another issue was the angle that the engine sat at with driver on board. If it tilted too much, oil would be trapped in a puddle over the exhaust pipe (negating the shallow drainage slope to the sump well).

[Steve.k]

Guys i had no idea they running that hot. Ive had filled blocks hit 240 quite easy on dyno pulls. We would set up fans and cool down. Dyno guy did not like 240 at all. Would not fire up till back below 200. 240 to me seems plenty warm but 260-300 wow!

[Vintagewrench]

The shop racing car is 1967 Volvo 1.8l four w/o an oil cooler that gets raced often in vintage races at Line Rock Park and at a hillclimb 5 or 6 times a year. It is operated at WOT most of the time and the oil temp gets up to 260 and stays there. We use Valvoline VR1 10-30 racing oil because of the flat tappet cam. On a race weekend the car covers as many as 250 miles and afterwards the oil gets changed and the oil filter is cut open when back at the shop. After 1500 miles of on the track competition we have never had a bearing or oiling issue and the oil never smells like it has been burnt.

From what I have learned and read about modern engine oil it can operate at higher temps then was possible in the past.