Cold oil changes

[ahramin]

Is there really anything wrong with draining the oil cold for an oil change? If you just leave it drain for a couple hours are you getting that much less out of the sump than when it's hot?

[Heliian]

Oil flows better when hot, we know that. It's a little easier on a hot engine and that may help the new oil going in to flow down better. Theoretically, moisture would be drawn out with the hot oil whereas if it was cold, the moisture gets drawn into the new oil. Sometimes it may not be practical to warm it first and I think that that is okay once and a while. Just try to plan your next one after a flight or something. I wouldn't try it cold at -20 but +20degC is warm enough.

I think you'll see a few different opinions here.

[photofly]

I've measured the amount of oil I get out with a hot engine, and a cold engine, and if you wait long enough there's no discernable difference.

Also, I burn my wrist a lot less reaching up through the cowl flaps to put the tube on the quick-drain when the engine is cold.

[SuperchargedRS]

Why are you making things harder on yourself?

[anofly]

i like to drain mine after a flight of an hour or so, all the muck is "probably" up in the oil, rather than settled on the pan. Just out of interest if that dirty oil is ok to land with, why is it too dirty to go for a warm up flight?. Lots of shops that work on aircraft that have sat a day or so waiting for their mtce turn, warm them up with a ground run. cheers

[Greysierra]

In my personal opinion, the only advantage to draining the oil after a flight or warm up run the speed in which the oil drains.

A pre inspection ground run is beneficial for the detection of possible defects prior to the aircraft coming into the hangar (pressures, temps, mag drops etc.).

[cgzro]

If you preheat the engine a bit with hot air you can do a cold oil change fairly easily. I occasionally do this when its too cold to fly but i need to change the oil.

To preheat I put an electric hot air heater under the engine, direct the hot air into the bottom of the cowl. Put a blanket on top, wait an hour or two and its nice and toasty either to fly or drain the oil.

[ahramin]

That's a good idea but it doesn't get that cold here . Faster to just go for a 1/2 hour flight.