interesting conversation about draining oil

[the Ferret]

Since I woke up it's been pouring rain. Might be the first day this month I won't get to ride. So my other bike needs it's oil and filter changed, might as well do that today. Was talking to one of my good riding buddies this morning about what he was doing instead of riding today, and he was basically doing the same to his bike on this rainy day.

He says "are you going to warm up the bike before draining the oil?"

I said "I always do, don't you?"

He says "nope, the last time I rode it the oil was warm and when I parked it, all the warm oil drained down into the sump".

I said "yea?" questioningly, like, where are you going with this?

He says "well, if you start it again you are just going to push dirty oil from the sump up into the top of the motor again, where it has to drain back down, so you can drain it from the sump".

I said "That's true, but won't it drain faster from the sump when it's warm?"

He says "Ever open a bottle of oil that's been sitting in your garage for a few weeks?"

I said "yea?" again wondering where he's going with this

He says "did you have any trouble pouring it out of the bottle?"

Hmm now he's got me pondering. Since I was a little kid I was told to heat up oil before draining it, but he's got me thinking now. All the dirty oil did drain down when I last came in from riding and parked the bike I have to assume. Do I really want to push that dirty oil back up into the top of my engine now?

Oil might not get changed until tomorrow. I have to work this out in my head. He may have a point.

What do you think?

[12cb96vfr_imp]

I do it cold personally.

[Paulb_imp]

Maybe the rule of warming the engine goes back to times when oil was really thick and not as we know it today. I bought a Vintage speedway bike earlier this year and the engine is a 1947 J.A.P 500cc single which is designed to run on Castrol R (smells great). When I disconnected the pipe from the oil tank to the engine to drain the tank nothing came out for ages and finally it flowed as a tiny line, almost breaking into single drips. I checked with Castrol to find a more modern oil to use but they said this engine was designed to run on Castrol R and warned me to warm the engine quickly to heat and thin the oil otherwise the head would not get lubricated properly. So, I think your friend is probably correct and modern oils do not require old fashioned drainage rules.

[ss2wheels_imp]

I think like every other oil thread it makes no difference one way or another, just change it when you are supposed to and it will be good to go

[coach50_imp]

I change the oil cold on all my bikes & cars. As long as one waits a day or 2, all the oil that's going to drain down will have by then. Of course, as posted above the "cold" oil viscosity ratings for vehicles are lower than in back in the day...

[jmc1100_imp]

I doubt a dealership would pay the time to warm an engine before an oil change. Sound advice...

[silverbub_imp]

If you are using 10W30...then maybe the question is whether you want an ambient(cool) drain at ~10 weight... or a warm to hot(operating temp) at ~30 weight?... To me... flow rate would be of some consideration so as to flush out the "gunk" residing in the sump pan...I go with a "warm-hot" drain after a nice local ride... have lunch(whatever)...then drain & let drip for some time...I have gotten about an extra 8-10 oz of accumulated dripping by leaving off drain plug for a reasonable time(an hour or so) after the initial drain flow...I presume you are talking about your ST1300 here & so am I...

[Tim_in_AZ_imp]

Not so much the flow rate of the warmer oil, but any 'gunk' that has settled has a chance to be put back into suspension so it is flushed out.

[the Ferret]

I just thought it interesting. I had never heard of anyone changing oil cold, had not been taught that way and never considered any other way than changing it warm. Another wives tale? Or is there science behind it?

The part about reintroducing dirty oil (and it's contaminates) back into the top end is what really got me to thinking.

Tim makes a good point too, putting gunk into suspension so it can come out, but how much of that gunk will get trapped in the head/oil lines/and on our bike (oil cooler) if you heat it up and circulate it through the system?

Unlike a typical oil thread, this conversation is relevant no matter the brand or weight.

Also had not heard of anyone changing gears without the clutch though lol

I must live in a cave lol

[silverbub_imp]

Not so much the flow rate of the warmer oil, but any 'gunk' that has settled has a chance to be put back into suspension so it is flushed out.

Yes, that too, certainly!... Thanks for clarification... flow rate AND SUSPENSION OF 'gunk' GOOD!