Towmater

Currently, I'm seeing oil temps of about 200f. Usually about 10f above my coolant temp. When I'm towing I have seen 250 at which point I slowed way down to try and get it to cool off.

What is every one else seeing?

Do we have a thermostat that opens the oil cooler?

peter2772000

Conventional oils start to break down at around 275*F, synthetics get that bumped up to about 300*. Contrary to what you might think though, oil temps below water-boiling temps (212*) won't allow any water/condensation in the oil to boil off, causing acid build-up in the oil.

So in theory, your typical oil temps are low, if anything. But I suppose it depends on where the oil temp is being measured. It'll be cooler in the sump than in between the crank/conn-rod bearings. In the end, I'm guessing your temps are just fine.

kajtek1

There is reason car manufacturers don't put oil temp gauge for average driver and even coolant temp gauges most of the time are dummy gauges who will not show normal temp fluctuation.
Too many owners observe the gauge not understanding it and panic just in case.
There are lot of myths about oil temp. Like ATF should stay in 200's F. I used to have bus with transmission retarder, using transmission pump for slowing 16 tons beast down.
That was raising ATF temp to 350F and even that was older, dino fluid, it was ok with it.

Towmater

It's nice to hear the theory, but does anyone watch their temps while on commuting or towing?

I race quite a few different cars in different classes and unless we're changing fluids every race we try to keep the oil 240 and under.

If I'm towing 5k lbs over Vail pass I'd like to do the same.

I wonder about the trans temp but there isnt much I can do except service it more often as I dont know of any coolers for the 7g.

kajtek1

My cars with 7G do have ATF cooler, build into radiator.
Is changing oil more often lowering its temperature? New oil has lot of detergents, so I wonder how running the engine on more soap can lower the temperature.

Towmater

Of course not.

But eventually the oil will vaporize at high temps, see NOACK testing. I usually swap in some nice diesel amsoil stuff when I'm making my long tows. (18+ hours per day)

kajtek1

Diesel can tow all day without any special care.
How many of those 18 hr you keep gas pedal on the floor?
I used my Ford Powerstroke for pulling 30,000 lb combos over Sierra and some of that on dino oils.

PSDCampervan

A laser-point trigger temperature gun might bring a little piece of mind, I think Harbor Freight sells them for ~$20. I keep one in driver's door pocket. I haven't towed anything but typically see readings w/ laser of 160-190 F temp at oil filter housing lid. Coolant reservoir typically shows 130-150 F & top of oil cooler in valley typically shows 180-190 F after a several hour road trip @ 65-80 MPH in 95 F ambient air temperatures. What I find peculiar on this engine is difference between right bank & left bank valve covers. The right side (passenger side) of engine typically runs 20 degrees hotter than left for some reason. I have never seen it the other way around & do check often. Long story short, different parts of engine topside run at different temperatures but oil cooler & oil filter housing probably most closely represent what's happening internally imho.

Towmater

Interesting idea. I can try that.

My theory on the drivers side v passenger side is on the passenger side is the dpf and exhuast.

Etienne Lau

I would not try to correlate or relate coolant temperature with oil temperature. There is a huge discrepancy between the two, especially driving in cold weather. Diesel engines in general take much longer than gasoline engines to build up heat, this can be seen when your cabin temperature in cold weather takes a long time to get warm. Oil temperature takes even longer than that to heat up. I have driven at least 10 miles here in Dallas winter time and it is at that point the coolant temperature makes it past 90C. The oil temperature? Its still hovering around 50-60C. Oil by its very nature does not fluctuate in temperature dramatically and very quickly. Oil temperature will always be higher than coolant temperature once the engine has truly reached operating temperature. And tend to stay high by its very nature. The Oil cooler helps speed up some of this cooling off.

As other have pointed out, oil is designed to withstand far higher temperatures than the coolant. So it makes absolutely no sense to try and keep the oil temperature at or near the coolant temperature. Check out this website regarding oil temperature: https://www.hotrod.com/articles/engine-oil-temperature/

Basically you actually do want to see temperature 100C or higher in oil to burn off the water and other deposits collecting in the oil. Keeping oil below 100C is probably more damaging to the oil and engine. Keep in mind this is sump temperature and as other have stated, the oil temperature you see is probably not measure in the sump or we do not know where it is being measured.