Do I measure oil levels when the engine is cold or warm?

Our owner's handbook doesn't have any specific instructions on checking the engine oil while the engine is warm or cold.

As far as I'm aware, some of the newer cars with electronically controlled oil level modules require that all checks be done while the oil levels are worm.

Also, has anyone over filled on oil and ever dealt with a burning oil smell coming from the engine bay after?

 

Most of the advice I've heard is to check when cold. I think your owner's manual would state otherwise if applicable - sounds like not so much in this case. If I check warm on my car, I get a very different reading from cold. I always checked my IS when cold and got plausible results.

If you overfilled the oil, might be a good idea to drain off the excess ASAP. Overfilled oil seems like a bad thing though I only have my Googling as far as knowledge on that topic.

 

The most "basic" answer would be to run your car for a few minutes then wait about 15-20 minutes for the oil to settle then check it. I personally check it when I wake up and it's cold then another time after driving it and then letting it sit for about 20ish minutes. I obviously only check it like every other week if that.

 

I think its normally suggested to check when warm. However I've always checked when cold. If doing an oil change I check cold, start the car let it idle like a min or so, check again. If you're checking warm after a drive probably give it a few mins to settle before checking and it should be reading higher warm than when cold. Thats why if I ever feel the need to check when warm I always check again later when cold.
Just my theory. I really don't know what the experts say should check that out lol.

But more importantly if you're too full on oil you want to fix that like today. I too would have to Google the reasons right now but trust me they're valid I've seen a few of them come to life. Depending on how much its not something you want to leave let your car work out on its own.

 

For me ideally checking when it's cold is the way to go.
At that point the filter should be full, a film of oil all over the engine interior, and the rest of the oil collected in the pan.

After an oil change I will start the car, and once the oil light goes out, shut it off. If you're lucky that should be about 3 seconds at most.
Then I check the oil level.
Once again at that point the new filter should be full and the oil distributed throughout the engine to coat everything, and the rest sitting in the pan.
This is assuming too that I warmed the engine up before the oil change.

 

My mechanic accidentally slightly overfilled my 350...he put like 7.2 qts instead of the 6.5 or whatever it calls for. What I did was take a thin rubber hose,put it down the dipstick tube and siphoned out a half quart. Don’t do it when oils hot, but it worked perfectly for me and is easier than lifting car up and draining.

 

Half a quart isn't anything to worry about. You'd get higher levels of sloshing from just sitting in your car or going over a speed bump. I verified this back in the day by pulling the oil pans and doing some measurements because this same thing used to float around before.

In fact, some of the BMW track guys used to over fill by 1-2 quarts on purpose back in the day. I did on two of my M3s. They did that for a decade or more. So 1/2 quart isn't a big deal. If all it took was a 1/2 quart to make or break you, you'd total your engines every time you took a turn. The engine is a very dynamic violent place. And yes i'm well aware of crank aeration.

As far as when to check it, best to check when warm and after the engine has been shut down. Depends how the dip stick was designed to be calibrated.

Though at the end of the day, a dangerously low oil level will be low regardless of the temp of the oil. And of course no oil will always be no oil. So check whenever.

 

Not sure I'm on board with half a quart over being ok.
Personally anything more than a quarter of a quart and I'd be draining off the excess.

And dedicated track cars are purpose built and shouldn't be compared to street cars. Street cars you want to last 10 years at least, track cars just need to last 10 hours on a race weekend then you can rebuild during the week.
So it's like comparing apples and poodles.

I guess if it's ok to go above and beyond the manufacturers design oil capacity for the engine, when is too much, too much.
Is 1 quart over ok, is 2...is 3...why not just double the amount of oil in the engine...that way you're sure everything is always lubricated...is there even a line in the sand anymore.
Maybe you can overfill you CT with 2 quarts and let us know what happens in 500 miles.

The reality is when you start to increase the volume of oil in the engine, this then reduces that space available for the natural pressure that builds internally when the engine is running...hence why we have PCV systems.
If that pressure is now higher than the PCV system can handle, well, it has to go somewhere, and it's gonna take the oil with it...this is when seals, all of a sudden, start to leak. The pressure and oil will find the weakest point and escape the engine.

 

I also read on the internet (so must be true) and makes sense, too much oil will cause it to be come foamy, and foamy oil doesn't provide the needed lubrication.
Air pressure being off. Air kind of mixes with the oil, becomes foamy. Something to that extent.

 

Exactly...that was the "crankcase aeration" mentioned in E46CT's post.

 

It was mainly my OCD kicking in. But it only took me 10-15 min to Mcgyver a pump and siphon out a half quart.

 

Speaking of, I just had this arrive:
Unfortunately I just recently did the oil change on the Lex, so I'll be breaking this in on my Highlander in the next week or two.
The Lex will still require crawling under it to get the filter, but then I don't need it that high or need to get under it that far if I don't need to get to the pan.

 

Nice, that will come in handy. I waited until car cooled down than stuck a thin tube down the dipstick tube into the oil pan and pulled out the excess.

 

Thank you everyone for your input/advice.

Is it normal for my oil level to appear higher when the engine is cold? There's a pretty significant difference when I measure the oil level cold versus warm (~1 hour after driving).

 

yeah sorry I had it backwards before. Should be higher when cold be cause its all sitting in the pan. Right after running will be the lowest, thats why it was suggested to wait after running and check while warm. Personally I like mine at the top line when cold. About a half inch difference looks familiar. Just if it were me I'd add some, but don't take just my word for it.