Duramax Engine Oil Cooler

[HH]

Since we are on the subject, what is the highest recommend temperature for synthetic oil and dino oil in an engine?

[Stlheadake]

Since we are on the subject, what is the highest recommend temperature for synthetic oil and dino oil in an engine?

I don't know and would be interested, but what I really want to know, is how many out there HAVE a guage for engine oil temp? I never thought of putting one on my liquid cooled engine. I routinely put them on my Dirt Bike (which is also liquid cooled), or air cooled riding mower.

hmmm? Now I have to get another A-pillar cluster and guage....I need a doctor's note, my wife won't argue with a doctor's note...

Calling Dr. Kennedy...

[Hubert]

Don't know about synthetic. Of course they can tolerate higher temps but that doesn't mean its ok for the engine to be hotter see below.

For dino oil the higher the temp the shorter the life expectancy and it varies depending on where you read.

For avg oil pan....
Some like no more than 180~190F which is what I have kind of settled on as its close to coolant temperature and thus is helping cool the engine more. Others say higher is ok. I'll say above 220F is getting hot and shortens life some. The hotter it gets it gets exponential. Say at 260F it should be changed at maybe 1/2 maintenance schedule time.


Of course its engine dependant oil sump size and some other little things but
Kubota says 240F continuous is max and intermittent max is 266F for avg oil temp measured in middle of sump. If above it indicates engine is overloaded. As in probable the piston is really hot from high EGT and heating the oil up.

[HH]

For avg oil pan....
Some like no more than 180~190F which is what I have kind of settled on as its close to coolant temperature and thus is helping cool the engine more. Others say higher is ok.

I know I asked, but I seriously doubt that 180 - 190 would be the limit as the oil is subjected to much higher temperatures being close to the combustion.

After posting, I read the second part of the above mentioned article and he states something like 360 as max temperature. So where is it measured, and anyone have an idea if this is a good number?

I have an engine oil temp gauge and it runs around 220 - 230F unloaded and near 270 - 280F pulling a trailer. I am running 15W-40 synthetic and measuring the temperature right before it goes to the cooler. I am using a tube and fin cooler.

[Hubert]

I am not saying that 180-190F is a hard limit. Yes even dino oil can withstand higher than that. Synthetic cand withstand higher than that. I am suggesting it would be an optimum max continuous temp as to really help cool the engine and take some of the load off the coolant. Also would help keep the piston a bit cooler and help keep it from swelling then gualling under heavy load.

I have never seen a GM spec for max oil temp. And it varies depending on the sources I have read for oil limits.

I have read Kubota's application guide for thier small IDI diesels and they state 248F for continuous and 266F intermittent as limits not to be exceeded. That is measured as "avg" oil temp in middle of oil pan. Its not the only indicator of engine load but it is a hard limit and if you can't keep oil temp below the above specs then they don't approve the application for warranty claims. ie if you run it hot and guall a piston (one the first things that happen for them if run hot) they don't fix it for free.

Now intermittent is rarely clearly defined for these type specs and depends on actual item. Its sometimes stated as duty cycle based on continuos time. Intermittent isn't very long usually and really more a possible high max limit that marketing keys on to show high numbers.

I'd say the oil temps you posted are a bit too high for optimum oil life for dino oil. You are fine because the other key temps limits are in check. Key indicators of load and application EGT, ECT, IAT, oil temp, engine compartment temps. You are generally ok if one is high but its not good for 2 to be out of range if 3 get out of range it leads to trouble 4 would cause damage more than likely (depending on how far over limits).

If you look at maintenance schedules for heavy towing or severe duty they recommend shorter intervals. I think just one of the reasons is due to this higher avg oil temps. Other reasons could be heavy use means more fuel burned and thus more soot and higher temps and more fuel combusted mean other contaminates that dilute additive packages.

[Hubert]

Any one have any other engine company numbers to compare?

I would guess max continuous oil temp would be based mostly on piston cylinder clearance??? As oil Temp., EGT, ECT, and IAT would be the only way to infer upon the piston temperature and thus how tight it gets in the bore when hot and "expanded" or if it is approaching melting or softening temps???

From some heat testing I was envolved with on some Kubota naturally aspirated diesel engines the oil temp tracked right along with ECT and EGT. If either of those were high then oil temp was too. This particular set up had an ECT guage and "murphy switch" and would kill the engine if ECT hit 230F. It appears they size the radiator such that it can't overcool the block as in if EGT and oil temp get high then the coolant will "runaway" as in get too hot and shut the engine off to protect it. Now a quick load up will soar EGT and won't save it. But that's the application technicians job to heat test the application and measure each of the key indicators again EGT, ECT, and oil temperature for normal steady state operation. If all indicators stay within spec then the engine should handle the application. If one is high they should closer examine the loading or reject the application.

I did see some oil temps in 240F range and ECT high but ok. So I don't think its the oil limit its more a combination and inferences.

For the 6.5 GM seems to key on the IAT and ECT together to know the piston may get too hot as that is what triggers defuel. I further suppose they have done some testing and probably its the CHEAPEST (and meets similar repeatability and reliability guage testing) to ensure the OBD system can protect against engine internal damage from hard use (high heat).

[Hubert]

Maybe a good reference:

I googled Deutz (air cooled /oil cooled ) diesel engine. And one reference stated max oil temp was 125C (257F). I guess thats an avg temp and the oil gets hotter at certain points like engine coolant. The air cooled fins max temp is 170C (338F).


http://www.magirusdeutz.co.uk/MD8deutz.htm


Still looking around.