Manual mentions warm up engine, turn off, and wait 5 minutes. But to avoid overfilling, why not check when engine cold?

 

No reason to not check the oil when it's cold. That's when I usually check my oil. In principle, oil does expand when hot, but that's too small a change to worry about.

I have a feeling those instructions were written by a mathematician. He knew that if the car was running you need to wait a few minutes for the oil to drain down. So rather than have separate "How to check when the car is cold" instruction, he just did "Run the car and proceed as in the previous problem."

The other odd instruction is to change oil when the engine is cold. Oil should be changed when hot, or at least warm, so the gunk in the bottom of the pan will flow out. I suspect that's the doing of the lawyers, who worry about someone burning themselves while changing oil.

FWIW, I routinely burn myself changing the oil in my Accord and my wife's Camry. Oil filters on both are on the other side of the exhaust. But if it doesn't hurt you don't get that real feeling of accomplishment.

Ken

 

I have a 6 month old burn on my arm from a toyota camry. Is your wifes a 4cyl? As for hondas I just lay a rag or two on the exhaust while I do the filter. I do the filter first then the oil.

 

Expansion of the oil, and it allows you to get a correct reading when the engine has come up to it's operating temperature.

When an engine is cold, the oil drops to all of the lower crevices. So when you check it cold, it might read it as low. But when the engine is warmed up everything as expanded and moving around, it will read the correct reading.

I'm explaining from a piston motor stand point...so please correct me if I am wrong about the rotary. (I'm still holding grey areas about the engine)

Topping off oil while cold = overfilling
Topping off while @ operating temperature = correctomundo!!!

 

Oil does not really expand. I check it warm because when it is cold it can drain out of lines, the filter and other parts of the motor. I would rather my oil system be full and not just the pan.

 

The Camry is V-6. The oil filter (which is at an upside-down angle) is on the front of the block under the exhaust manifold.

Never thought of the rag trick for the Honda - that would certainly work. There's enough room, though, that if I pay attention I can work around it. The Camry is just tight, but at least it's worked from the top and I can minimize the burns by taking my time.

FWIW, I always drain the oil first, then work on the filter while the oil finishes dripping out. Adds to the challenge of being under the Honda.

Ken

 

i drive my car, park on a level surface, wait five minutes, check oil. only because the manual says to. i never start it when its cold and then wait five minutes to shut it off to check the oil, i'm too paranoid about flooding.

 

Since the dawn of internal combustion engines: check oil when engine is warm. As others have cited this ensures you're checking it near its operating range. Adding too much oil, in most vehicles (not so much the rotary), is worse than running low.

 

V6 camary is even worse. I do the same thing lay a rag on my forearm and old it by the end with my other had to keep it there.

 

Im not too keen on reading and believing everything the manual says... heck it says to use 5w-20, and to stray away from synthetics... LOL I use Royal Purple 5w-30 and RP synthetic ATF

 

I have a low threshold of pain, which means that I'll flinch and pull away before the burn gets too deep.

And (to stay on topic, lest we be scolded as threadjackers) I usually check the Camry's oil cold. When I check after a change, though, the engine is hot and but the new oil is cold. I wonder how that fits into the different opinions here?

Ken

 

And these are crevices that aren't reached by warm oil?

C'mon folks, it isn't that hard of an experiment:

Stop the car, wait the 5 minutes, check the oil level. Go in the house. Later, or the next day when the car is cold, go check it again. Then you will know the difference between a warm and a cold check.

 

^agreeed....We're not talking about a qt. of expansion to the fact that it will be easy to overfilll I ALWAYS check/fill mine when it's cold and i've been fine...I'm guessing there would be no more than 5MM of change on the dipstick between cold and warm....

 

I'd be surprised if it was even that much.

For goofs, I tried googling this topic, to see what the Internet says. After all, that's the authority on everything. It kind of went both ways, so our arbiter of truth is a bit schizoid.

The amusing part was stumbling into oil change DIYs. Most were fine, although there was a split between sites that gave the right way and the wrong way. The most interesting DIYoid was a site that said that when you refill the oil to pour in the amount your owner's manual says, and to not trust the dipstick.

FWIW, the most important things are to check oil with the car on level ground, and to make sure you stick the stick in all the way for the measurement. If we take Mazda's five munute instruction to mean at least five minutes, that covers both hot and cold.

Ken