Engine temp before oil change?
- Thread starter Buckeye88
- Start date
I warm my cars about half way up, maybe a mile of driving. By the time I get it up on the stands heat isn’t a problem. Semi warm oil drains just fine.
I run it on the highway for about 5 minutes and then drain it.Let it drain till oil filter isnt hardly warm.
I let the engine coolant get up to operating temperature then turn it off. Seems to be a nice medium between warm oil but not scalding oil.
No difference at all. The engine oil heated and cooled at your last drive before oil change (for the believers of suspending particulates in oil). Cold engine that sat overnight is easier to work on, has all the oil back in the pan and will easily offset the faster hot oil flow even when cold. I wish I could do that but have to drive to my brother garage and put it on ramps. If I have my garage I'd jack it cold and drain.
You can change it after a drive. You can change it first thing in the morning.
Cold, you won't burn gloveless hands and it may be more controllable.
Hot will go faster, primarily.
Either way, the end result is the same. Use method that best fits your day, change filter as well and change with confidence.
Cold, you won't burn gloveless hands and it may be more controllable.
Hot will go faster, primarily.
Either way, the end result is the same. Use method that best fits your day, change filter as well and change with confidence.
To me the most significant advantage of changing the oil warm is that the bearings and pistons have been fully oiled at least within the last hour or so before that first post OC start where engine is going to run dry for 3-5 seconds before oil pressure is reestablished.
A cold oil change creates the opposite scenario. The dry start occur on an engine where the oil has had all night to drain out of the places it most needs to be.
A cold oil change creates the opposite scenario. The dry start occur on an engine where the oil has had all night to drain out of the places it most needs to be.
"Best" is a word that means whatever you say it means and is undefinable to any standard.
Factually, as many have said here already-If we exclude gear oils ( slightly different set of rules) and set an ambient oil temp around 70-80F.
The warmer oil will normally in most cases drain slightly faster measured against a timeline. ( completeness of the drain is virtually the same as gravity is the prime mover assuming the time is allowed). The same galleys and so forth will still hold the same volumes cold or hot.
Cleanliness is a different matter but contrary to commonly held beliefs...
Engines do not "mix" or agitate particulates ( and even many chemicals) well. There is no auger, blade or mixing well or even static vessel to create either continuous suspension or ensure particle distribution. Its not even a good fluid agitation- more of a "slosh" effect.
So that means that particles will drop out of suspension based more on gram weight and geometry relative to viscosity and Sg than simple thermal qualities. A case can also be made that some particles are actually held to the case ( sides of the internals) due to the tackifiers of the oil and surface roughness. ( yes that happens frequently)
Surfactants and detergents, the same depending on condition of that specific oil prior to change.
So, change to your preference because from a performance perspective- any difference is going to be virtually insignificant relative to any routine engine life consideration.
4WD
$50 site donor 2024
Here is how the “best” temperature is determined:
Start engine … come off high idle … pull up on ramps.
Go get oil, filter, funnel, drain pan, & rags from my garage
Open hood, place oil & filter above radiator for Kodak moment
Change oil & filter … clean up … get odometer picture … zero OLM
I change on a cold engine unless it's due a change and the only time I can get to it is after driving. I've had several engines go well over 200K without any problems and the engine in an '88 Ford Escort had 518K miles when I quit driving it for other reasons. The '88 did use oil but it didn't start using oil until about 250-300K miles.
4WD
$50 site donor 2024
518k on the Escort and never burned on hot parts ! I’m just saying
For quite a while due to Bitog, I used to drive it to get it to full operating temperature. Then as time went by I began to think it's a waste of time and money. So I cycled back to how I did it since I first started doing my own oil changes. I start the engine drive a few minutes, get the vehicle in the air if needed and change the oil. The contaminants are in suspension, and I don't have to wait that long to safely deal with hot oil and engine parts. I let the oil drain for at least 30 minutes, sometimes longer if the lawn needs to be cut or I have something else to do. They oil is thin and flows out fast. If I plan on doing a UOA I will drive at least 25 minutes, which is a fair representation of how the vehicle is used.
Never said I wasn't burned on hot parts, just not changing the oil. Really the Escort was a very good car. I pretty well kept up with maintenance and the only times it ever left me stranded was for a bad fuel pump and premature timing belt failure. I can't complain, I think it left me on the side of the road 3 times. That's not bad in 518K miles and often driving 200+ miles a day. Even those times it was within a few miles of home so I had it towed home and repaired it. When we moved from NC-KY in 2010 I drove it the 500 mile journey and it had over 500K miles on it then. At the time I was hoping to get a lot more miles out of it but, things started going bad on it and having chronic back pain I didn't feel like taking care of the problems myself and wasn't going to pay someone $50-100 an hour to work on a car with half a million miles on it.518k on the Escort and never burned on hot parts ! I’m just saying
Last edited:
This is the best reason to change it after it has ran for at least a minute and not sat overnight
I've heard this before. In 1982 to be exact. But I don't know enough about car engines to understand it. What's the difference between starting your car in the morning after it sat all night or cut multiple days and starting your car after an oil change? All the oil that was going to drain back into the pan from the upper engine has drained back so there is no difference between oil film after an oc and after sitting overnight. The pan is full after an oc and after sitting all night. Therefore the difference must be with the oil pump. The pump is empty and needs to get primed after an oc. It takes 3-5 seconds to get the oil pump primed and oil flowing to the engine?
Full warm up. It drains sooner. I’ll drive a few miles, sometimes jump on I-39 to the next exit and back. Not much traffic here to slow you down unless they painting stripes or the pavement buckles.
I typically do this after it's warmed up/driven but I see no reason why cold would be an issue and I'm sure I've done them cold before. Intuitively warm seems like it would allow the most to be drained and the best "mixing"/reduction in "stuff"/residue left in the engine.
If warm oil has particles in it, whats the oil filter doing?.,,,
