Warming up oil in non running motor?

[18Bravo]

I want to change the oil in the three project bikes I have. To my knowledge, none of them run. Short of using a blowtorch, how do I heat that oil to get a good drain?
On a side note, my commander thirty years ago used to fill the motor with diesel after draining the oil, and crank it a few times with the spark plugs disconnected. While I don't think this is necessary on a well maintained motor, it there some sort of safe solvent that can be run through the motors after draining to get any old sludge out?

[shinyribs]

If none of the engines have been running then you probably don't need to worry about it too much. Time is more important than heat.Even the coldest oil will drain out in an hour or so, unless we are talking about oil that has been at sub-zero temps for a long time. When it quits dripping you're good.

Re:sludge. Unless you are willing to go to the effort of removing the sludge you may knock loose ( physically cleaning internals) I wouldn't bother, but that's just my opinion. If there is sludge lurking in a corner somewhere, that sucks...but I don't wanna dislodge it if I don't have a means of removing it. It'll just fall out in lumps before it will dissolve back in to liquid that the oil filter is able to catch. Personally, I've never bought in to flushing engines. I mean, if I think there is something harmful in there, suspending it in flushing liquid and then circulating it through the oiling system seems odd to me.

Valvecovers, oil pans and oil pumps are extremely easy to remove. If you clean inside those areas you pretty much got it all.

[18Bravo]

Thanks. Looks like they're draining all day tomorrow.

[easyrider12]

I  used to put a small electric heater fan under my 750 when it was near freezing and it warmed the whole thing up.  My old trick for first startup of the year.  The bunch on history channel would use a wood fire, lol. 😉