Checking oil

[frankprozzoly]

I was reading a debate wether to check oil cold or after operating temperature. Isn't the rule to always check when engine is warm

[PA DETAILER]

Should Oil Levels be Checked when Engine is Hot or Cold? (http://www.mobiloil.com/USA-English/MotorOil/Car_Care/AskMobil/Checking_Motor_Oil_Levels.aspx)

I always check it COLD. You want the oil to drain back into the crankcase. If checked HOT, you would not get a accurate reading.

[frankprozzoly]

When I check oil cold im about a quart low same with my Harley. Even the Harley dealership said check warm. I always have more oil on dipstick after a warm engine. And that's after it's wiped. Its not residual oil. I'll read the link you posted

[swanicyouth]

You should really be checking the oil warm to hot for two reasons:

1. The oil will expand slightly when hot, you want the reading to be accurate as of operating temperature.

2. Most (all?) manufacturers recommend checking oil 5-10 mins after the engine is shut down - how could the like be "cold" if the engine was just running 5 minutes ago? No manufacturer, I've ever seen, said "check oil cold after sitting overnight". Some manufacturer's even specify checking the oil warm/hot (Nissan) in the owner's manual.

[Dogfather]

There's some mildly interesting reading on this debate over at BITOG.

[PA DETAILER]

I do stand corrected. It is indeed stated in the manual.

1. Idle to operating temp.
2. Shut off engine and wait 10 MIN.
3. Obtain your reading.

[RMM]

...
2. Most (all?) manufacturers recommend checking oil 5-10 mins after the engine is shut down - how could the like be "cold" if the engine was just running 5 minutes ago? No manufacturer, I've ever seen, said "check oil cold after sitting overnight". Some manufacturer's even specify checking the oil warm/hot (Nissan) in the owner's manual.

:whs:

[FUNX650]

in the manual

•Let's see...(thinking out loud):
-If I go with the thermal coefficient for the expansion of motor oil (gasoline engines):
0.00088/K with a rho of 870 kg/m^3 = _________

-Nah...Forget that!!!

•The Owner's Manual: Yep...
-A pretty good source of "oil-information"...
to just go ahead and follow.

Bob

[CDot]

You should really be checking the oil warm to hot for two reasons:

1. The oil will expand slightly when hot, you want the reading to be accurate as of operating temperature.

2. Most (all?) manufacturers recommend checking oil 5-10 mins after the engine is shut down - how could the like be "cold" if the engine was just running 5 minutes ago? No manufacturer, I've ever seen, said "check oil cold after sitting overnight". Some manufacturer's even specify checking the oil warm/hot (Nissan) in the owner's manual.


I do stand corrected. It is indeed stated in the manual.

1. Idle to operating temp.
2. Shut off engine and wait 10 MIN.
3. Obtain your reading.

Yep and Yep; also many manufacturers have a upper tick mark and a lower tick mark for what is acceptable at "Hot" and "Cold" temps.

It's my non-ASE-educated theory that part of this is because of the tighter clearances in newer engines + thinner viscosity oil; the drainage may be much faster.

[Paul A.]

I've always liked after it's run up to temp and then shut down. Something about the oil thinning out and letting it fully draw down to the reading point while it's hot or at least warm.

[KillaCam]

I've always checked mine warm after the car has been shut off for about ten minutes.

[KMdef9]

No debate, always check fluids warm. You want to measure at operating temps, not shutdown temps. Now, some fluids can measured with the vehicle running and others cannot.

The only fluids you check cold, are the ones that have a cold level and a hot level on the dip stick or on the reservoir. I.E. Coolant, power steering...