PCMO Temp Range

[Scott88]

What average oil temps would you expect to see in a light duty vehicle (V6/V8 with 195* t-stat) with a 5 quart capacity. Obvisiouslsy several variables play into this answer, but in general will oil be around coolant temps or much higher?

Also, what is the upper temperature limit for moderm conventinal PCMO?

Thanks.

 

[racer12306]

My van generally reads oil temp in the 180s but will go up into the 190s on occasion. Coolant temp is generally mid 190s.

 

[SOHCman]

I believe the oil gets up into the 250-300 range in certain spots in the engine. On heavy duty engines you will see air/oil and coolant/oil coolers to keep the oil temp down to these levels. Oil typically doesn't get as hot on ight duty non turbo engines, it's all very dependent on design and use.

 

[NateDN10]

In general terms, the bulk (sump) oil temperature is often near, but under the water temperature once warmed up. However, there are numerous exceptions.

The Noack volatility test heats the oil to 150C (302F) for 1 hour, and <15% of the oil must evaporate for the oil to pass the test.

 

[ARCOgraphite]

Sump temp is one thin,g but thin film temp (off the piston underside and thru the oc rings) and cascading off the ex ports in the heads can easily get over 130 - 150C. This is what sludged the garbage conventional 5w30s of the 90's

 

[CATERHAM]

Originally Posted By: NateDN10

The Noack volatility test heats the oil to 150C (302F) for 1 hour, and div>

The NOACK test is at 250C.

Mineral oils will start to rapidly oxidize with sump oil temp's of 130C. Syn' oils can handle oil temp's of 150C without a problem.

Typical oil temp's are a maximum of 90-95C and you have to be doing something pretty aggressive such very high speed driving or towing a heavy trailer up hill where a lot of WOT is used to get oil temp's above 100C in most NA applications.

 

[dparm]

Sump temp of 200 F seems to be fairly typical for passenger cars. With a synthetic, I wouldn't worry until you approach 300.

 

[CATERHAM]

Originally Posted By: dparm
With a synthetic, I wouldn't worry until you approach 300.

The oil may be able to handle 300F sump oil temp' but the oil viscosity may get too thin.
If your normal oil temp's are 200F and all of a sudden you see 300F you know something is wrong unless the vehicle in question is known to see those kind of oil temp's like on a race track.
Once you know the normal oil temp's for your engine, anything above normal should have reason, and if you can't think of one then you should be concerned; i.e., is there debris blocking the rad' or oil cooler (if you have one) that sort of thing.

 

[dparm]

A fair point, Caterham. For most performance cars, moving up to 300 is probably safe. A more pedestrian vehicle...perhaps not.

 

[HTSS_TR]

Someone posted engine and oil temps a while ago in his vehicle after driving for 20-30 miles on highway at normal speed (around 70-75 MPH), bulk(sump) oil temp was about +/- 10F of the engine temp.

 

[Sonataman]

Mine typically runs 10f above coolant temps. 195f

 

[bigt61]

I used to run a 355 V8 Camaro road race car and the highest temps I ever saw were a little over 240F water and 300F oil - in a half hour SCCA race. The engine probably didn't like it but it survived fine with no ill effects. I was using Kendall 20W-50 GT1 dino at the time. After I got a better radiator, the temps came down - on a hot 90F+ day I would normally get 215-220 water and 250 oil. I'm sure a modern synthetic racing oil would laugh at those temps all day.

 

[SteveSRT8]

As stated above it can get quite hot in specific areas, but average temp is what we can easily quantify.

I have had a few UOA's done in the early days of my 6.1 after track use and even with 300 degree oil temps M1 0W-40 maintained viscosity and oil pressure just fine in my engine without any detectable breakdown.

I'm pretty certain the squirters bathing the piston crowns probably ran much hotter oil temps in that region.

 

[Scott88]

Good stuff. Thanks guys.