Changing Oil - Cold engine or warm engine?

"nermal" (nermal) 10/21/2017 at 10:14 • Filed to: conundrums, fashion, bro, just take it to a quickie lube

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I’m planning on getting a haircut, teeth whitening, some highly fashionable coveralls, and doing an oil change this weekend. Do you warm up the engine before you change your oil?

PROs (allegedly): All the crap that’s sitting in the bottom of the engine gets suspended in the oil, and more of it comes out. Warm oil flows better.

CONs (allegedly): More likely to burn yourself. All the crap that’s sitting in the bottom of the engine is now all over the engine, instead of conveniently in the bottom.

dogisbadob > nermal 10/21/2017 at 10:32

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for me, cold

AkursedX > nermal 10/21/2017 at 10:40

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Depends on the car. If the filter is in a spot that I know I’m going to drip a significant amount of oil all over my arm when I take it off, I do it cold. If its in an easy spot, I’ll do it hot (but still prefer to do it cold if I can)

DutchieDC2R > nermal 10/21/2017 at 10:42

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Cold, but if youre gonna do it hot, why not wear a pair of latex gloves (or whichever type is firm to the hands yet protective to the heat).

benjrblant > nermal 10/21/2017 at 10:43

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In the land cruiser, I’ll usually do it warm. The FSM of the BMW F650GS says it must be changed when at operating temp, so there’s that. I generally think that there’s not much difference either way and you probably won’t have any long term negative effects of doing a cold or hot change.

Urambo Tauro > nermal 10/21/2017 at 10:48

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I do it hot, but not fast. No quickie 10min oil changes for me. My filter’s easy to get to, so I just bite my tongue and play hot potato with the plug and filter, then walk away and go do something else while it drains.

Twingo Tamer - About to descend into project car hell. > nermal 10/21/2017 at 10:59

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I always warm up the car first, takes forever to drain cold and doesnt clear out the crap as well.

jimz > nermal 10/21/2017 at 11:12

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I do it warm (drive the car/bike for a while then let it cool some) just because the oil flows faster.

All the crap that’s sitting in the bottom of the engine gets suspended in the oil,

that’s not how it works. All modern automotive motor oils have detergent additives. detergents keep contaminants in suspension so the oil filter can screen them out. Or if they’re non-solid contaminants, stay dispersed in the oil so they can be drained out when changed.

in general, if your engine or device has an oil filter, you use a detergent oil. if it does not have an oil filter, you use a non-detergent oil.

gogmorgo - rowing gears in a Grand Cherokee > nermal 10/21/2017 at 11:13

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When I was working in the fleet shop we always did it warm. Especially with some of the larger diesel pickups, it would take forever to drain them if you didn’t. We had one f350 cab/chassis with a utility box on it that had a 14L oil capacity. That’s almost four US gallons.

I usually do it warm at home, but I wouldn’t just let it sit idling just for the sake of changing out the oil. If I had no errands to run I would just do it cold.

vicali > nermal 10/21/2017 at 11:19

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Warm- only because it flows out the Fumoto better.. otherwise it takes 10 min instead of 5..

FTTOHG Has Moved to https://opposite-lock.com > nermal 10/21/2017 at 11:23

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I try warm. The trick is to wait so it isn’t quite hot. Otherwise I burn myself on the plug and it drains too quick splashing eveywhere and I end up with oil all over my garage floor.

just-a-scratch > nermal 10/21/2017 at 11:32

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Cold for me.

Captain of the Enterprise > nermal 10/21/2017 at 11:42

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Warm it’s supposed to drain better and faster

wafflesnfalafel > nermal 10/21/2017 at 11:44

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Always warm, (doesn’t have to be searing hot, but you want as much to easily flow out.)

Maxima Speed > nermal 10/21/2017 at 12:05

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I do warm so it drains easier, that being said I don’t change it at operating temperature. Usually I either let it idle up to 3/4 to half operating temperature and then change it or I’ll drive around a bit get it to operating temperature and then let it cool off for about 15 minutes or so, that way it’s warm I’m not likely to get burnt. On my car I have to reach the oil filter from the top of the engine bay, reaching under the exhaust manifold.

KevlarRx7 > nermal 10/21/2017 at 12:13

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Warm, more flows out and it’s quicker.

cluelessk > nermal 10/21/2017 at 12:24

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Depends on the car. Burning yourself sucks.

415s30 W123TSXWaggoIIIIIIo ( •_•))°) > nermal 10/21/2017 at 12:35

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I don’t do it myself anymore, three cars no garage and disposal etc .. but I have magnetic plugs so hopefully that helps with debris. I would think warm is betterand let it sit for a few minutes. But if its a pretty warm day it should flow out of there ok. I bring my oil and filter to a place and my friend services the Z when he checks my carbs. I am useless tuning triple carbs.

BritishLeyland™ > nermal 10/21/2017 at 12:57

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Warm. Unless the oil filter is worryingly close to the exhaust maifold or exhaust components.

CalzoneGolem > nermal 10/21/2017 at 13:01

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I pay my mechanic to do it because I find the process and disposal annoying.

diplodicus forgot his password > nermal 10/21/2017 at 14:43

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I do it at operating temp because I just got back with the oil and I’m impatient. Never had an issue burning my hands draining. I wait 20-30mins to remove the filter since it’s under the headers. I only fill it so that the dipstick is at 3/4 to the full line approximately. Then once the engine has fully cooled and I check it the line is on the full mark. My owners manual says the best oil level readings are when the engine has been sitting for a few hours so your mileage may vary.

jminer > nermal 10/21/2017 at 17:04

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I like to take the car/bike out for a longer run (atleast a half hour) to get everything up to temp and then let it sit for an hour. By then the exhaust is cold but the oil is still hot enough to flow well. It does take some planning, but it has always served me well.

merged-5876237249235911857-hrw8uc > nermal 10/21/2017 at 17:39

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Change it hot and change it often.

gettingoldercarguy > nermal 10/21/2017 at 18:46

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Warm, fumoto + easy filter removal makes it a breeze.