Check oil level (Diesel engine) Cold or warm????

[Northsea]

A quick simple one for you.

Don't have my passat owners book on this so wondered what you pros say about this.
I assume it doesn't really matter as long as the car is level and the oil has had enough time to settle.

Personally I usually only remember to check it after driving so leave it a few minutes till I check it.

Any thoughts on this one please guys.

Thank you.

[manity]

personally id do it cold as there is a fair bit of oil pumped around the engine which takes time to settle somewhere between half and a litre. so if you top up the oil to max mark could end up being too much oil in there.

[Rick 63]

You can do it warm,but wait about an hour as previous post says give any oil time to drain back into the sump. To get a true level.

Rick

[Northsea]

Thanks for the comments guys.
An hour!

Pleased I never fill it up to the absolute max if that's right enough.
I just give it 10 minutes or so.

So I take it when you do an oil and filter change you never top it up to max till after you've run the engine briefly to let the oil in filter then let it cool down for this length of time?

[Rick 63]

If you have changed the oil filter you could over fill by the amount the filter takes. Otherwise the oil level will be low,you can get the correct amount of oil it takes including the filter from your handbook or dealer. Then put that amount of oil in before you start it up, them let it settle before a final check.

Rick

[vwcabriolet1971]

IMHO an hour to allow the engine oil to drain down into the sump is OTT Where on earth is the oil going to hide between 10 mins and 1 hour ? With the low viscosity of modern engine oils ( say 5W-30) it doesn't take long for the oil to drain down . If the oil is reasonably up to working temperature ( coolant temp 90deg C) then it's already quite thin and will flow quite quickly . Admitedly the warm oil will not be as dense as cold oil but the difference must be quite small. As long as the engine is not overfilled with oil there should be no problem . It is important that the oil be checked when the car is on level ground. Some cars can give wide variations on oil level readings if the car is not reasonably level.
Some car manuals can specify incorrect oil capacities. If you're not 100 % sure on the oil capacity when refilling after an oil change, it's better to fill up to the maxm. dipstick level and then run engine for a few mins. to fill up oil pump / filter etc & then re-check after say 15 mins ( cold oil) & top up as neccessary. It's better to be 0.5L down than 0.3L too high .
Obviously the much higher viscosity gearbox oils should be allowed to settle for much longer. I often wonder how long does a busy commercial garage allow for gearbox oil draining & re-filling of cold gearbox oil ?
The few times I've ever drained gearbox oils is that it seems to take forever ! ( & re-filling is not much quicker !) - Best planned for long lunch breaks !