Oil temps and time to burn off

Joined
Nov 18, 2007
Messages
640
Location
NJ
So, I have read that you need to get our oil temps up to 212F to burn off contaminants. My question is, how long do you need to see these temps?

The reason I ask is that during the winter, for me to get to these temps I have to drive in a lower gear and keep RPMs up. For instance, I can be on the highway for 20 miles and the temps may not go above 178 - 180 unless I'm putting some stress on the engine by going up a hill. My Subarus have a manual mode where I can go highway speeds and drop to 3rd, 4th, 5th, etc... I usually will go down to 4th at around 70MPH and I can get the temps up to 212 and sometimes closer to 217 but if I say go up to 5th gear the temps will slowly drop and if I go back to full auto, they may drop to 194 for example. Obviously, driving in a lower gear blows through gas so I was wondering how long do I need to see 212F or higher.

If this has been covered, I apologize. I didn't see it when I did a quick search.
 
It's not so much contaminates that need to burn off, but condensation and possibly fuel. The theory is that short tripped cars don't have time to steam off the water or fuel in the oil which leads to increased acids in the oil or thinner oil. Acidic oil depletes the anti-acid additives more quickly. Acids in the oil can contribute increased corrosion and bearing wear.

I don't think you need to worry about getting the oil over 212f, though. Getting the oil up to full operating temperature on the highway like you are should be plenty to drive off moisture. The clothes in your dryer dry out without getting up to 212f.
 
And to threadjack/piggyback off this question, it's talked about often to drive easy until the oil is up to temp. Does that mean full operating oil temp like in the 190F range? Or are we good to get on it at, say, 140F?
 
Is there even any evidence that fuel burns off? I have never read any literature explaining when (and how) this occurs.
 
And to threadjack/piggyback off this question, it's talked about often to drive easy until the oil is up to temp. Does that mean full operating oil temp like in the 190F range? Or are we good to get on it at, say, 140F?
You are good over 100F in my opinion…modern multi Viscosity oil is moving and working at that temp.
 
Read this tonight - exam at 0900 …

 
Read this tonight - exam at 0900 …

Just the 2 minutes I read went way over my head. I'm an IT guy man... ;-)
 
  • Like
Reactions: 4WD
Is there even any evidence that fuel burns off? I have never read any literature explaining when (and how) this occurs.
The fuel in the crankcase doesn't "burn"
Any unburned fuel that makes it past the pison rings will be a vapor.
The crankcase evacuation system is meant to draw those vapors out.
On a cold engine, those vapors can condense and mix with the oil.
 
I totally agree! But everything I read says 212F burn off, etc...
Correct, since 212F is when water will begin to boil, but in a healthy engine driven under normal circumstances with regular OCI’s there shouldn’t be much condensation in the oil.
 
I doubt my oil ever quite gets to 212 F

I used to have a particular problem operating an air cooled motorcycle on a short commute in the winter. The oil wasn't getting above 140 -150 F. As long as I removed the dipstick when I got home, any signs of mayonnaise were gone by morning. That mixture of oil and water that had condensed in the dipstick hole was even lower than the 150 F oil temperature but the water still evaporated. It's not so much a lack of oil temperature that causes problems but a lack of adequate breathing in modern engines.
 
As pervious posts mentioned, as long as the engine isn't short tripped often you should be ok. By short tripping I mean less than 10 min, I would imagine the engineers designed the engine to get the engine up to temp as soon as possible as it both reduces the emissions as well as allows the engine to run more efficiently - likely the typical commute is ~15 min. Also, remember the temps you are seeing at the gauge are only an indication of the oil temps at that specific location and the actual oil temp may vary depending on the location, in fact will inevitability vary; for instance the oil cooling the piston or nearing the piston rings will be considerably hotter and will instantly evaporate any moisture and contaminates out through the PCV. If the engine isn't quite up to temp, I'd imagine some of the moisture in the oil will even make it past the piston rings as the water molecules are smaller than oil and be burnt that way as well.
 
What the oil temperature sensor sees is an average of the whole oil capacity, so parts will be higher and parts lower depending on what the oil is doing. I would speculate that oil control rings will see higher temps than a timing chain.

For my experience with a CVT equipped QX60, when it is very cold out ( lower than -13C) and the engine is just started, the programming of the transmission is set to keep revs high until the CVT fluid is adequately warmed ~ about 5-10 minutes and then the revs will drop down and all is back to normal. The CVT has its own electric heater to warm the fluid, so from what I'm assuming the engine could still be cold but if the CVT fluid is happy, then the car should act normal. I would assume Nissan / Jatco is more concerned about the transmission than the engine?
 
Water boils at 212F, but it starts to evaporate much lower.

If you really want to raise your winter driving temperature, temporarily, block off some of the radiator with a piece of cardboard.
 
Kind of same boat as OP, in the Maximas you need summer weather and 1 hour drive with stop and go to have engine oil temp to like 210F at most. Of course on Auto mode these CVTs are fragile as s*** you don't wanna load on them with higher RPM for long.
 
Not sure about the hair splitting - if it did not come in that motor oil jug - it’s a contaminant …
Each of them have been “discussed“ in numerous threads …
OLM systems model for them as well …
 
Back
Top