Engine temp before oil change?

[spasm3]

I would take a sample after your typical drive. That way you know the results match your driving habits, especially if you are a short trip driver. It does no good to typically drive 5-7 miles , yet drive 15 miles to get the oil hot for a sample. Not representative of typical use.

Especially important when evaluating fuel dilution in a DI engine.

 

[demarpaint]

I would take a sample after your typical drive. That way you know the results match your driving habits, especially if you are a short trip driver. It does no good to typically drive 5-7 miles , yet drive 15 miles to get the oil hot for a sample. Not representative of typical use.

Especially important when evaluating fuel dilution in a DI engine.

Exactly! No point in skewing the results, the same can be said for a car driven an hour to and from work for the majority of the time it is used. A five minute run before taking a sample is not a fair representation of how the vehicle is used either.

 

[4WD]

Running large industrial engines … the OEM wants oil samples taken from a cooler loop at operational temps and engine loads. No sump oil samples allowed.
But if draining a PVL in the driveway … I do it warm and a few times I have poured 1/2 quart of clean oil in and that’s out the drain hole pristine and immediately …
Two things I’m not doing:
Getting hands burned - or an UOA when I used top shelf oil within recommended OCI.

 

[Sam_Julier]

I drain the oil at operating temp. Always have. Usually find something else to do for 30 minutes to an hour and then finish.

 

[CheezWhiz]

I think just running it a few minutes will stir it up enough.

this makes sense to me. for a thicker oil maybe it makes sense to let the engine warm up some, but for a 5w30 or 0w20 i don’t see an issue?

 

[ofelas]

this makes sense to me. for a thicker oil maybe it makes sense to let the engine warm up some, but for a 5w30 or 0w20 i don’t see an issue?

It's a moot point, considering a hot 15w40 is far thinner than a cold 0w20.
Oil, when gravity assisted, flows best while hot.

 

[CheezWhiz]

It's a moot point, considering a hot 15w40 is far thinner than a cold 0w20.
Oil, when gravity assisted, flows best while hot.

sure but how much cold 0w20 is realistically going to be left in the pan compared to warm 15w40? as long as you run the engine long enough to circulate the oil thoroughly, i'm not convinced it matters much whether you reach operating temperature or just drain cool but recently recirculated oil.