Changing engine oil (Hot or Cold)

when i service cars i run them first to get oil hotter for reason above thinner oil

Change it hot but don't burn yourself-
A good compromise would be to change it when warm...

Hot - more oil runs out.

If you have tough hands then it's ok, but otherwise wait 2 beers and it'll be uncoimfortable but wont burn....

As an ex mechanic your skin gets used to it - but your wife don't get used to the grease stains on everything.......

Always hot, the oil will flow quicker. Just wait a few minutes extra to allow the oil in the top end to trurn to sump

NOT HOT!!!!!! REPEAT NOT HOT...
Dont come back from a day trip and jump under the car...

Again NOT COLD....

Hot will burn you to the bone if it hits your arm as you remove the plug.

Cold will be too thick... Warm is the go... Run it for 3-5 odd mins at idle.....

Warm oil is thinner and runs our easier....

Kev, We always run vehicle up to normal operating temp, or drain oil on return home after day's work. Have the luxury of drive on service ramp, so often leave vehicle to drain overnight. Don't know if I'd be too keen to get under hot vehicle, if had to do it goanna style! Hot is best for diesels, as their oil often gets "gluggy" towards end of oil change interval. Have plenty of work shirts, with "shrapnel marks", from removing plug, on very hot sumps. Hooroo...

Draining your oil hot is better as it flows easier and also because contaminants in the oil are in suspension because your engine has just been run. If you would then leave you oil to cool down eg overnight before draining, then some contaminants will seperate from the oil and be left behind in you engine. Drain your oil straight away after it has been run.

I might be missing something here, but.... When the engine is cold didn't the oil spend several hours dripping down from the upper galleries etc from when it was last hot? So the only places in a cold engine that contain oil are the filter canister and the sump? If you crank the motor you send cold oil everywhere, and then have to wait for it to slowly return to the sump. The sump plug is big enough for it not to matter whether the oil is thick or thin. So I reckon, provided you don't crank the engine, you will retrieve more old oil and crud from a cold engine.

I've always done it when hot for the thinner oil reason but have never really thought that it would matter significantly.

I forgot to add that you also need to ensure the vehicle is parked at the right angle to let all the oil drain out the plug hole. On some vehicles this means running one or both wheels part way up a ramp.