Drain oil, hot or cold?

[Doc_Bob]

Drain oil, hot or cold?

I used to drain my engine oil hot. Then, one day, as I was burning my hands, I asked myself, why? Why do I heat up the oil, and then work around a hot engine with hot oil dripping all over? My brother told me he does it to have the oil drain out quickly. Hmmmmmmmmmm, I said, I have plenty of time.

So, now I drain my old cold. Stone cold. It works and I like it. I just remove the drain plug, set the pan and then go eat dinner. Maybe watch a movie. Maybe go to bed, maybe wait until the morning. (<- being a little silly). The point is I just let the oil drain until it stops. Takes a little longer cold, but not having to work around a hot engine or get splashed with hot oil (<-ouch!!).

So, do you drain your oil hot or cold, and why?
Bob

 

[BobRip]

If you run the engine first, it mixes the sediment into the oil. Then when you drain it the sediment runs out with the oil. If you drain it cold the sediment (metal, dirt, etc.) settles into the pan and may not come out as much. Then when you put in clean oil it is instantly dirty. At least this is what I have heard.

Bob Rip

 

[MrJimi]

Both of you guys make sense, I drain mine warm and have a few cold drinks and it works good. I have a Chevy S-10 that turned 200K today and I can go 2,500 miles and the oil is clean and don't go down either, Oil is the cheapest insurance for an engine, Think about that.
Jim

 

[PineRidge]

Bob it's not strictly a matter of time or we would all be draining our oil cold. Oil is drained after the engine has warmed to help flush out any impurities, chips or the like that remain in the bottom of the oil pan that the oil filter didn't catch because they settled out of the oil.

I drop the drain plugs in the pan where I drain the oil so I never feel the hot oil. When the time comes I fish them both out (there's 2 on my machine) with an ordinary magnet. No mess, and no fuss.

 

[Mike_Lipke]

I drain mine at precisely 105 degrees F. That is the perfect temp for a shower as well.
At that temp, all the sediments are still mixed in, and I don't have to handle the drain plug like it is a hot potato.

One time, I was just ready to change the oil, as it was exactly at 105, and my brother called, and I talked to him for 10 minutes. I got back out there and the oil had cooled to 96 degrees, and I had to start the engine to get it back up to 105.
Well, I let it run too long and it got to 111 degrees F. What a bummer.
I had to let it sit for 12 minutes to reach 105 again.

Long day. But it was worth it to do it right.

 

[D7E]

You gotta drain them hot,If you don't you don't get everything out cold oil is thicker so it sticks to the sides and the pan and hot oil has all the sediment mixed up in it so it comes out with the oil not still sitting on the bottom of the oil pan.
on new stuff you probably don't notice it because they keep the oil cleaner anyway but motors with lots of hours will black the oil real fast if you only drain it half assed.
we usually drain then as soon as they come in the yard from a days work and refill em next morning.

 

[SteveInMD]

Here's how I see it...

If you drain it cold it has had a long time to drain down into the oil pan from up in the motor, i.e., since it last ran.

If running your motor stirs up a bunch of sediment in your oil pan, you've got bigger problems to worry about than your oil temperature.

 

[Dargo]

If you use a quality oil filter, i.e. not a Fram, there is a drain back valve that will prevent unfiltered oil from going back down into your pan. Also, if your filter is worth a crap, the suspended particles you mention will be trapped in your filter. This is information as printed for ASE Master techs. The old "warm your engine to suspend particles" was first written back when engines had NO oil filters on them. My '62 Chevy engine had no factory oil filter. It would make sense to warm the engine first then. Otherwise, unless you use junk oil filters, I don't see the need. Then, if you use junk oil filters, why bother to change your oil? You can save another $10 bucks or so by not doing that in addition to saving $2 for a junk oil filter.

 

[PineRidge]

One thing about free information is that everyone has their own opinion.

 

[Highbeam]

I got tired of burning my hand on hot exhaust manifolds. I can deal with a toasty drainplug though. So here's my hybrid approach.

I do the oil change on a fully warmed engine but I don't shut it off and change it right away, instead I let it cool to the warm state. On my tractor I start the cold engine and let it warm up to a pleasant temperature before shutting down and changing the oil right on the trailer in the morning before putting it to work. This allows the oil to flow out more quickly, suspends the particles, and puts oil into the all the bearings before dumping the sump. Remember that when you start the engine after a filter change there will be several seconds where no oil pressure is present. If the engine has recently been bathed in oil from being run then it seems to me that the residual lubrication will help the engine survive this no oil condition better. Compare that to a cold engine where all the oil has drained off to the sump and drained out, the mud is setting on the bottom and the upper bearings dry. New fresh oil will eventually get there but the diesel makes lots of compression and that cold start is hard even with oil pressure.