Checking oil when engine is warm/cold

[loudsubz]

No mention of this in the manual. I normally do it cold but have read in some car manuals to check when its warm to prevent overfilling. The oil when its cold is right at the "Add" mark on the stick.

[jester]

If you want to make sure you do not need to add then check it when it is warm and if you are still around the Add mark i would add some more.

[mmandley]

Engine oil doesn't expand as much as hydraulic type oils such as Trans and power steering or even like antifreeze and this is why its confusing.

You can check it when its cold or hot doesn't matter. Normal what i do is at least start the engine for a minute let it circulate and pressurize your system. Then shut it off and check it. It your worried then add oil till its right in the middle of the low and full. Even at low the engine can lose another quart before its dangerous. Even at full it can hold another quart before its dangerous. Its designed this way to compensate for the human factor.

[maxpower220]

When the oil is "cold", all of it has drained back into the pan. Therefore, you know how much is in the engine. Checking it hot will still have some oil in the heads, cylinder walls, etc and that is why there is a difference. You should not have a difference of bottom of the stick vs full in these 2 readings, the difference is minimal. If you do, recheck the way you are looking at the dipstick.

With steep angles of surfing, I would not run the oil at the bottom of the stick.

[cab13367]

When the oil is "cold", all of it has drained back into the pan. Therefore, you know how much is in the engine. Checking it hot will still have some oil in the heads, cylinder walls, etc and that is why there is a difference. You should not have a difference of bottom of the stick vs full in these 2 readings, the difference is minimal. If you do, recheck the way you are looking at the dipstick.

With steep angles of surfing, I would not run the oil at the bottom of the stick.

I'm with maxpower - I always check engine oil cold whether car or boat for the reason he states above and I think the manufacturers mark the dipstick based on all the oil being in the oil pan, i.e., cold engine. Everything I've ever read says to check engine oil with a cold engine.

[loudsubz]

I too was under the assumption to check when it was cold as I have always done so on other cars/boats, but my new subaru states in the manual to check when engine is warm/right after driving to allow for thermal expansion.

[mmandley]

Not to start a hair raising thread, but you realize for the last 90 years cars been around they check them Hot at the service stations all the time. :D

[squeeg333]

I've always checked mine in my vehicles when the engine was warm. Drive it for at least 15 minutes, turn it off, let it sit 5 minutes, and then check the oil. The 5 minute wait allows the oil to drain back into the pan.

I think either way you go, just be consistent. That way you know exactly your level when cold, or when hot... you'll have a difference (though slight) between the two, but if you always do it one way, then there's no question.

[cab13367]

Not to start a hair raising thread, but you realize for the last 90 years cars been around they check them Hot at the service stations all the time. :D

Yes, because they have no choice. It doesn't mean that's the right way to do it.