Oil Change - Hot or Cold

[Jeff70]

Originally Posted By: Jeff70
When I change my oil I do it after the car has been in the garage overnight. I jack it up put jackstands under it early in the a.m. pull the drain plug and forget about it for a couple of hours. The way I look at it is this, when I parked it, it was hot and all the oil in the engine has had a chance to make its way to the oil pan so when i drain it and leave it for a couple of hours the vast majortiy of the oil should have been drained. I have never been a big fan of a "quick" oil change as I feel they do not get enough of the old oil out.

IMO change the oil when its cold, pull an oil sample when its hot and use a tube for the sample not the drain, as this is the way aviation does it as well. BTW I have been an A&P mechanic for about 18 years now.......


Guess I should have explained a little more. I use Amsoil motor flush every other oil change. So when I use this I have to do it hot, and its very hot as the engine runs at fast idle for several mins. But I still pull the drain plug and leave it for a couple of hours, as I never change my oil when I'm pressed for time. So as for sludge and the talk of blocked passage ways, I beleive the inside of my engine should look outstanding as I take care to make sure my internals are as well cared for as the exterior of my car.

 

[Dyoel182]

Originally Posted By: [RT
ProjUltraZ]i'm gonna try it cold and see if more comes out. makes sense


Why would more come out when it wont flow as well?

 

[Junior]

Everyone has their preference. My top 10 reasons for changing oil while warm

10)Some oil film still on engine parts for dry start.
9)Oil flows out of pan faster
8)New oil warms a bit as it runs through the head and down to pan
7)Warm engine does not jump to high idle upon start up.
6)IMO items 10 and 8 provide better start up protection when the filter is empty during the first start after change.
5)Plug is out for less than 5 minutes. I don't care if there is a little oil left in engine. IMO it is statistically insignificant.
4)Oil running down arm is nice and warm while laying on cold concrete
3)Warm oil is closer to flash point when dumped on neighborhood bonfire
2)all lube should be warmed before use

And the number one reason!

1)Burnt hand makes cold beer taste better.

 

[[RT] ProjUltraZ]

i was thinking if it's all in the pan, then you just have to think about pan flow instead of all the other passageways

 

[fcbuff]

2)all lube should be warmed before use



Nice!!!

 

[REDDOG]

Hot

 

[[RT] ProjUltraZ]

Junior's #10 and 7 give me pause for trying it cold.

i do fill the oil filter with new oil, but the high idle on the 350 V8 w/ no oil is indeed a disturbing sound until the new oil circulates

 

[Dyoel182]

Why does it idle high? Did you really let it drain long enough that the engine cooled down that much?

 

[FrozenPilot]

Normally on a hot engine, but I will do it cold if its summer time. During the winter, I want the thing warm so I don't freeze so bad when I'm doing the change. I think it was 35F during the last change I did, and I don't have a garage. Even did a tire rotation, just to warm me up.

 

[harley145000]

HOT