Oil change - hot or cold?

[Rudejake]

So what's everyone do, change their oil when the engine is hot or cold? Seems that the common practice is to do it when the motor/oil is hot. The oil is thinner and flows better, etc.

I prefer to do it when it's cold for these reasons: Less danger... don't drop the drain plug into the drain pan, get burned on the header/pipe, no hot oil down the arm. When you change oil right after running the engine, the top of the engine has more oil in it and takes longer to drain to the pan. Change it hot and all the crud and metal that you're trying to remove is scattered throughout the engine. Change it cold and most of the particles have had time to flow down and settle out in the oil pan.

So how's everyone else do it? Am I missing other reasons for doing it hot?

[foreverford]

In my eyes warm is best, heat it up, let things settle (or flow back to the pan) and then drain it. If you drain it cold you don;t get all of the sedement out. this is all minor thou if you change it often enough, according to how it is driven, and the wheather. And don;t forget if you use an all synthetic good brand of oil the vescosity doesn;t change! it doesn;t get thicker or thinner. But I do beleave in running the motor to get the oil moving in (the pan) not so much the motor to get anything that is clingging to the pan where the oil levels full mark is. you know RING AROUND THE PAN!

[jdrawlings07]

Getting the filter off when it is hot might burn you because of how you have to get to it, but it all depends how the car is raised!

[canadasvt]

Definitely hot.

[BGK]

Warm up the oil immediately before changing. I believe this is because if the air temperature is extremely low and the engine is cold, the oil will not flow or drain correctly or completely.

[LMarx]

How about a happy medium.
The oil should be warm, but the engine should have stood for at least 30 minutes to drain down to the pan. An hour if the weather is hot, as everything will stay warm a long time.
This is the best of both worlds. After an hour all the oil is drained down, but the oil has enough heat to flow out of the pan, taking the maximum of the dirty oil.
The worst would be at a dealer where a cold engine is started, driven inside with out really warming the oil, and the "cold" oil is drained after spreading through out the system. This is probably the situation with the winter months and leaving your car all day while at work. Better to say your waiting, and have the oil change while the engine is "hot".

Anyway, waiting until the HOT things have cooled on the external of the engine is common sense. It just requires some prior planning for the wait.
Good luck,

[imajsdaddy]

Hot for 2 reasons... 1 hot oil flows better... To the drain plug hole....

2 wouldn't feel like I'm bonding with the car if I didn't leave burn't skin on the car somewhere!

[DiscGolferGreg]

Always warm since it's usually done after coming home from work. :)

[keilhauer]

Warm, rather than hot. A tip is to remove the oil filler cap. This helps to prevent a vacuum in the engine as oil is drained out by allowing a 'flow' of air top to bottom to aid in the dispersal of oil. Think of filling a jug of water and turning it over to empty it. The oil 'glugglug's it way out as air tries to get back in to fill the void. Punch a hole in the bottom (top) after you've flipped the jug, then let the water come out and see how much easier it is. Same thing will happen to oil draining out of the engine theoretically.

[Rudejake]

A tip is to remove the oil filler cap.

Yep, I've always done that. I always let the car back down if I have to jack it up to change the oil. It's amazing how much extra oil some engines will hold when only being lifted a few inches. I swear the Focus dumped at least another 1/2 quart when sitting level.

[foreverford]

Hot for 2 reasons... 1 hot oil flows better... To the drain plug hole....

2 wouldn't feel like I'm bonding with the car if I didn't leave burn't skin on the car somewhere!
Number 2 was a good one but don't forget that if it is full synthetic the vescosity stays the same. take some mobil 1 put it in the freezer for awhile then compare its pouring abilities to some room temp. mobil 1 syn. and it will pour the same. then to see really how much better mobil 1 syn. oil is then regular oil put the 2 side by side in 2 frying pans and turn up the heat and watch one start cooking and one not at all!