Checking Oil - hot or cold?

jimogr

Basic question here, when checking the oil level in the car should the engine be hot or cold? I don't know much about oil, but I assume it expands with heat as most liquids do.

I have always checked my oil when the engine is hot. But recently a friend who was doing the driving test said her instructor told her it is done when the engine is cold - she showed me a few documents which said this (driving test related) including the second post in this thread:
http://www.boards.ie/vbulletin/showthread.php?t=2055310617

So checking oil level - hot or cold? Or does it matter?

skyhighflyer

I usually check mine when cold as I'm sure all the oil had drained to the sump and will give an accurate reading. However, warm oil will usually drain to the sump quite quickly so checking it a few minutes after the engine has been switched off shouldn't be a problem.

I'd say as long as you don't check it immediately after the engine has been running you'll get an acurate enough reading.

Alun

I was always told to do it when the engine was warm, but to wait a few minutes after the engine is stopped to let it settle first. I'm not sure of the reasons why though.

L1011

cold - you'll not get a proper impression of the oil level if the engines been running because it'll be hot/not all in the sump due to being pumped to other parts of the engine.

s14driftking

my car has to marks on it one for hot and one for cold
i always check it first thing in morning when checking thou as this will give a more accurate reading;)

Slig

MYOB wrote: »

cold - you'll not get a proper impression of the oil level if the engines been running because it'll be hot/not all in the sump due to being pumped to other parts of the engine.

+1 and on a level surface. make sure its warm if your changing the oil though as it flows better

voxpop

always though it was best to check it when warm but about 10 mins after, to let the oil drain back

cpoh1

Simple answer is both! It depends on the car manufacturer and engine in question b ut your owners manual will tell you. On my old hondas and nissan its when the engine has been fully warmed up and swtiched off for a couple of minutes to let the oil settle. On other cars like the focus its from cold.

biko

Bah, checking the oil is for pu$$ies


I check warm

Nonoperational

biko wrote: »

Bah, checking the oil is for pu$$ies


I check warm

Yes. Yes it is....

Seth Brundle

Aren't you meant to check the oil level in many Porsches with the engine running and hot?

astraboy

^^^Correct^^^ Older 911's need to be checked with the car running, otherwise you might overfill and cause damage. Most run of the mill cars can be checked cold however.

stratos

engines checked cold, auto gearboxes checked running. Some cars have a mark for warm engine oil. checking the oil after the engine has been running can cause you to think the level is low, as some of the oil is still in the engine. If you add oil then and its too much, the level in the sump will be too high. The bottom of a piston hitting a pool of oil makes a very expensive sound. I wish I could get my cat to check the oil.

MarkN

My car doesn't have a dipstick. :rolleyes:

So the only time it will give a reading is when the engine is properly warmed up on the idrive.

Anan1

MarkN wrote: »

My car doesn't have a dipstick. :rolleyes:

So the only time it will give a reading is when the engine is properly warmed up on the idrive.

That's going to be a little scary when the car's older!

MarkN

When it's old?

It was scary when it was new!

Idiots in Joe Duffy sold me a car with barely any oil in it, they blamed the idrive on it.

I'm all for technology but it wouldn't kill them in include a dipstick.. just in case.

I would've always checked when the engine is cold in other cars though.

macroman

You should wait approx 20-25 minutes after engine has stopped to check the oil level - this allows the oil to settle so that you can get an accurate reading.