Change oil Hot or Cold?

[drifter420]

I was just thinkin as I'm bout to change the motor oil on my car.. Currently using XD-3 0W30.. Always changed and thought it would flow out better. But based on the rated number... a 0W in cold SHOULD be able to flow out much better then when it's hot where it becomes at least a 30W.

So changing oil would be better cold and you don't have to worry bout burning yourself??

 

[fred0803]

You live long enough you read just about everything...
whoo boy...

 

[Fordiesel69]

I like to do mine on weekends and I allow 2-3 hours at least for it to drain. I like to start off woth the engine at full temp. Just what I like to do. I have no idea why, I guess all of the years of owning a diesel, you had to.

 

[ProfPS]

I prefer changing it after driving and still hot. Whether these are true or not, I think that most of the contaminants are still suspended in the oil and have not settled in the oil pan. I also prefer to start the engine after a change when it is still warm to avoid the cold start high rev with a dry oil pump and low (I prefill my filters when possible) or empty filter.

I interested what others do.

 

[Oil Changer]

I was gonna respond but now I'm not too sure. It appears that you are just joking, but I'll give it a shot - I always change my oil hot, usually scalding hot as I plan an oil change after I have driven the vehicle. I would also pull the plug cold and let it sit overnight but I can not be sure that the women in my life would not jump in, move the sign out of the way that says "DO NOT START", start the vehicle and drive away. My oil changes are completed before I leave sight of the vehicle.

 

[Patman]

It's always best to drain it while the oil is hot, and if you're worried about burning yourself when removing the oil filter, just let the oil drain for an hour or so before getting to the filter.

 

[Gene K]

This is a joke right? No oil is thinner cold than hot.

0W-just means it meets the pumping and cranking standards that would approximate a sub-3.80 cSt @ 100*C straight weight conventional Group I oil when tested at -35*C and -40*C.

Viscosity of XD-3 0W-30 is 12.1 cSt @ 100*C and 71.0 cSt @ 40*C based on a MDS I found.

 

[Triple_Se7en]

I generally don't get stung by hot oil from the filter. My stings come from the hot oil upon removing the plug. No I don't want one of those Fumoto valve-types that leaves several ounces of oil in the oil pan. I'd rather get my special oil glove & hand all scalded.

 

[tenderloin]

Why is it best to drain it hot? If you drive your vehicle then shut it off, whatever is suspended in the oil is still suspended in the oil...but more of it has drained down into your pan as time goes by. Of course we get into diminishing returns, but the longer the engine is shut off, the more oil and impurities reach the pan to be drained.

If you drain it hot but just let it drain for a few minutes, most will get out....and if you let it drain for hours, then the oil that is still slowly draining into the pan and out the drain, is cooler..and according to the "drain hot" fans not carrying the impurities that you want removed by draining the oil when hot, thus defeating somewhat the purpose of the "hot " drain. In actuality, the effect would be the same as draining cold...except the longer the car sits, the more oil and impurities drain into the pan...and out of your engine.

Draining cold gets more oil and impurities out..because more oil and impurities are in the pan and available to be drained. Modern oil flows freely when cold. With it goes the impurities. Remember, the oil was hot and the impurities were suspended in the oil...all the way to the pan. Now some may have visions of these impurities settling in the bottom of a pan..too heavy to be moved in the cold oil as it is being drained. ..

If one thinks about it...that is rather silly.

 

[TallPaul]

Until some analysis is done on the residuals over many hot and cold changes we really can't say which is better, but I suspect there will not be a significant difference. In either case, if the engine was last shut down hot, it all drains down into the pan. The only difference I can see is that the cold change may leave a thicker residual film in the pan, but the hot change may leave more up in the engine, since it has not had nearly as long to drain down. I change it either way, whichever is convenient at the time.

 

[Triple_Se7en]

Ever attempt an oil change in sub 50 degree weather with the engine cold from the night before?

Kinda explains why so many choose to have the oil hot.

 

[Ray H]

Cold "0" viscosity oil is much more viscous than hot "30" viscosity oil. The reason multi-vis. oils are recommended in liue of, say, a straight 30 viscosity motor oil is to avoid oil starvation while attempting to pump that cold "30" viscosity oil from the sump to the engine's top end and force it through tiny passages in the process. The advantage of draining the oil while it's hot, soon after engine shutdown, is two-fold:

1) It flows better. (Duhh...)

2) Particulates too small to have been trapped in the filter that haven't had a chance to settle to the bottom will be much more likely to be carried out with the draining oil.

(What in the name of all that's slippery are some of you guys smoking, anyway?)

 

[tenderloin]

"Ever attempt an oil change in sub 50 degree weather with the engine cold from the night before"?


Living at the beach in Southern California I can say I have not had that opportunity

......but then again, the vast majority of people haven't either.

 

[tenderloin]

Ray H
"What in the name of all that's slippery are some of you guys smoking, anyway?")

It seems not the quality blunts that you are

Oil flows better? It is draining from a 3/8 hole (or so) in the bottom of a pan. Why the need for more flow then cold oil provides?

Some drain holes are almost the size of the spouts on oil bottles

As far as particulates too small to be trapped in an oil filter...You really believe that they are heavy enough or sticky enough NOT to flow out when cold oil comes pouring out? If you haven't tried it believe me, cold oil pours quickly out of the pan drain. Not as fast as if hot of course, but still plenty fast to create a flow so most particles that may have settled in the bottom of the pan get drained.

IMO you get more particulates out with MORE oil in the pan and drained cold, then you do with the engine drained hot and MORE oil still trapped in the engine.

 

[Rand]

I normally drain it hot but give it long enough for the exhaust to cool off somewhat..
ie park it on ramps when I get off work. then change into grungy clothes.. eat a snack.. then change.
If you are worried about getting the last drop out use ramps..
if your drain pan has the plug towards the back of the car

 

[Lex94]

I change my oil hot because pain lets me know Im alive.

 

[Bryanccfshr]

I miss Fram sure Drains. Oh well For you wusses like me who don't like having hot oil run down your oil and into your armpit leaving a nice 1st degree burn there is always the Fumato Valve. I like to to let the vehicle drain (preferably hot) replace the filter and get sidetracked doing other things..(I mow the Lawn, or mess around in the garden, I vacuum the interior of the vehicle I might rotate the tires). The last thing I do is put the lug back in and add the oil. Besides.. It takes a while for all that oil in the drain pan to cool down so I can fish the plug out. (I am joshing I have a magnet)

 

[Triple_Se7en]

C'mon tenderloin!

The colder the oil - the slower it flows - the increased chance what's sitting at the bottom of the pan stays there. If you want to change it cold with the floaties sitting at the bottom of the pan - then whatever floats your oil boat works for you - but not for me.

 

[Big Jim]

Perhaps my high school auto shop teacher was wrong, but he taught that you should drain it hot when you could because hot oil disolves the contaminants better. The better flow can't hurt either since you will have less sticking to the inside of the pan.

 

[427Z06]

Well it looks like that time for another home experiment. Someone willing to drain their oil from a hot engine for a half an hour, then put a large measuring cup under the drain hole and let it drain overnight?

Be aware that, depending on the engine, if you also remove the filter, you may have to prime the oil pump the next day.