checking oil level - engine hot or cold?

[VAGMAN1]

I was always taught to check the oil on the engine when it's stone-cold, but.....

ElsaWin recomends getting the engine temp to at least 60degC, switch off the engine then check the level in a a 'few minutes' so that it drains back in to the sump

who's right? personally I'd stick with checking when stone-cold, but I'm interested what others think/do

 

[amoani]

I was always told to check oil levels when the engine is at running temperature, due to viscosity and expansion. But to be honest, i really dont think it makes that much difference. The levels will rise minimally due to expansion so it isnt really worth worrying about. Hope this helps.
Regards,

Aaron

 

[The Slug]

stone cold, has never changed from years ago, so why now??

 

[fingermouse]

i would say cold, but i know in gearboxes at work if you fill them cold ( 1.5 lts) then when they r hot 0.5 ltrs will come out of the over flow port.

note this is on a unit that runs at 160 deg c

but ive always checked mine cold as my dad showed me

 

[Stewart]

The only reason you should check the oil cold is because traditionally, mineral oils were very thick and took a while to drain back into the sump so common sense dictated to check the oil in the morning where you get a more accurate reading.
These days with synthetic oils with the consistency of pee, it doesnt take long to drain back into the sump anyway.

Its just common sense, nothing do with expansion, I certainly hope my oil doesnt expand or change its properties that much.

 

[god_thats_quick]

I've always been told on modern cars you should check it a few mins after stopping on a level surface (rather important on the S3).

 

[The Slug]

(rather important on the S3).

Ermm why?????

 

[god_thats_quick]

I've see it make a huge difference outside my house depending on which way round I park (and it's not a really steep hill)... I assume the location of the dipstick is effected with how level the car is.

 

[The Slug]

i wondered why it was more important on the S3 than anything else, as opposed to the levelness of ground.

 

[neil.c]

You cannot check the oil if the ground is not level. There is about 1 litre difference from the full and fill levels on the dipstick, so if you check it when cold and it is between the two then all is well and good. If you run the car and are too impatient to wait for the oil to drain in to the sump then you could end up over filling it which would not be good or the cat

 

[god_thats_quick]

i wondered why it was more important on the S3 than anything else, as opposed to the levelness of ground.

Because I've got an S3 and I've seen the difference it makes on that, have not clue if the others are the same... probably need some english lessons to make my point a little clearer I think!

 

[amoani]

Its just common sense, nothing do with expansion, I certainly hope my oil doesnt expand or change its properties that much.

Engine oil expands when it is hot and contracts when it is cold, as do most liquids. Thus if you check the oil cold it will be at a different level than if it is hot, even if this is only marginal.
Also, the properties of oil do change with temperature, why do you think that engine oil should be at the correct working temperature before you rev an engine hard. The viscosity will change allowing the oil to move more freely around all the internals.

Aaron

 

[Grant]

Checking oil... how do you do that?