Oil change-Do it cold or hot?

Pennzoil motor oil
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you be surprise how much more oil comes out if you know where the engine pockets are....

for my integra, if i lift the passenger side maybe 1-2 inches, a new stream of oil comes out
 
Hot! I have the ramps and tools all set and ready to go. The filter has to wait until things cool down to the touch.

Originally Posted By: SteveSRT8
The really anal ones pour another quart through the engine with the plug out!


Heh. I'm too cheap to waste a whole quart, but did once rise with ~1/3 qt. of some nondescript oil I had leftover.
Generally, I content myself with letting the engine drip for a few hours.
 
I was taught to do it hot but I never do! When I was a Mechanic I often had to work on hot car's and got burnt a lot. I had you desire to get burnt working on my own car's! On top of that if you break the oil filter lose before the car has been started inthe morning it comes off super easy but if you get the car hot best have a gorrila grip or lots of room for a filter wrench!
 
Originally Posted By: calvinnnnnnnnn
was curious which way do you do your oil change?
when it is cold and majority of the oil is in the pan or when it is hot and still flowing to the pan?

i've always done it hot, but my last one i did it cold and it drained more because i added almost 4 quarts of oil when i normally put in 3.75 quarts.


Here's the best of both worlds. Drain it hot and let it drain over night ... this gets the most old oil at as possible. I remove the filter the next day when it's cold ... much easier, and then complete the oil/filter change. I've done oil changes this way for years.
 
Originally Posted By: JohnBrowning
I was taught to do it hot but I never do! When I was a Mechanic I often had to work on hot car's and got burnt a lot. I had you desire to get burnt working on my own car's! On top of that if you break the oil filter lose before the car has been started inthe morning it comes off super easy but if you get the car hot best have a gorrila grip or lots of room for a filter wrench!

Indeed. Ive done enough super hot cars why would I want to do one of my own like that, when I can just wait until it is more comfortable to work on.
I always change the filter first, then move back and do the drain plug..
 
Always hot~!
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I usually let it drain for about 45-minutes also,yup I'm one picky dude and proud of it.I might try the drain-overnight method sometime
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Hot drain Plus Compressed Air Blown down into valve cover area to push residual (pint) out = no waiting
Anyone out there using the technique?
 
Hot hot hot. Usually after a 30+ minute drive. Reasons are:

1.) Any particulates are mixed and suspended in the oil after the engine is up to operating temperate and the oil pump has been pumping for a while. On a cold engine particulates may settle to the bottom of the oil pan and stay there as the cold oil is drained.

2.) At operating temperature the viscosity is at a minimum and the oil drains more quickly and completely for equal drain times as compared to a cold drain.

If you want to get as much fine particulates out of your engine as possible during an oil change you must change the oil after the engine has warmed to operating temperature and engine RPMs have been sufficient to get the oil well mixed.

I haven't seen many engines where the exhaust components made it difficult to access the drain plug while the engine is hot, however I have see more than a few where a hot exhaust made it difficult to remove the oil filter without danger of burning yourself. In such cases I would recommend pulling the drain plug with the engine hot, then walk away, letting the oil drain for an extended time to allow the engine exhaust to cool to the point where the oil filter can be safely removed (maybe 30 minutes or more). Just don't forget that the engine has no oil and attempt to crank the car.
 
X2 ^^^ There's your documentation.

I'd be really concerned with a cold change for the above and this additional reason: if you are not able to prefill the filter your engine is running a long time without oil pressure.

The full and fast drain of a HOT sump is another reason we are no longer using Fumoto valves. The bottom of the sump was building up a layer of stuff I had never seen before!

I'm afraid it was due to the tiny trickle that those things flow compared to the stock drain hole.
 
Originally Posted By: Hethaerto
I prefer to let the warmed-up car run for about 15 minutes after I pull the plug. I'm sure to get out all the oil that way.


How long do your engines usually last after having been run for 15 minutes without oil?
 
Originally Posted By: SteveSRT8
X2 ^^^ There's your documentation.

I'd be really concerned with a cold change for the above and this additional reason: if you are not able to prefill the filter your engine is running a long time without oil pressure.

The full and fast drain of a HOT sump is another reason we are no longer using Fumoto valves. The bottom of the sump was building up a layer of stuff I had never seen before!

I'm afraid it was due to the tiny trickle that those things flow compared to the stock drain hole.


Nope, engineerscott's post is simply more of the same anecdotal stuff that gets repeated time and again. For the record, I'm not bashing anything scott or anyone else has said about this, I'm only saying that I've never seen any scientific documentation that it's beneficial to your engine to drain your oil when it's hot.

RE; Fumoto valve...Before installing mine I measured how deep the threads were in my oil pan, and when I found out the threads on the valve would be too deep, I cut a cross in the top of the threads with a very small grinder. Then, after using the valve for the first oil change, I removed the valve and there was zero oil left in the pan.

Your Fumoto only produced a tiny trickle? Maybe there was something wrong with it, cuz mine empties my 6 quart sump in about two minutes or so, although I've never timed it. And, if you think about it, as soon as it starts dripping it's the same as the full sized drain hole, cuz oil drips from a 1/4 inch hole just as fast as it does from a 1/2 inch hole.

Also, you mentioned your concern about a cold oil change in regards to not being able to pre-fill the filter? What did you mean by that???
 
Originally Posted By: engineerscott
2.) At operating temperature the viscosity is at a minimum and the oil drains more quickly and completely for equal drain times as compared to a cold drain.


Isn't the whole point of multi-viscosity oils is that they thicken when they warm up, rather than thin out? Specifically, they're thin (e.g. 5W) when they're cold, but thicken (to 30 weight, say) when they're hot?
 
Originally Posted By: heypete
Isn't the whole point of multi-viscosity oils is that they thicken when they warm up, rather than thin out? Specifically, they're thin (e.g. 5W) when they're cold, but thicken (to 30 weight, say) when they're hot?

You already asked this question and got an answer.

https://bobistheoilguy.com/forums/posts/1708268/

The W number refers to pumpability. The bigger number refers to kinematic viscosity, which is a different measure. The numbers mean different things and cannot be compared.

All oils are several times thicker at 40 C than they are at 100 C, never mind comparing cold start temps to operating temps.
 
Originally Posted By: ADFD1
Try pouring hot oil vs cold oil. The hot oil pours nice and easy.


I have no effective means of heating oil other than in a cooking pot on my stove, and that would likely result in my fiancee killing me.
shocked2.gif


Personally, I'd prefer to trust the viscosity-measuring machines, and they seem to indicate that hot oil (100C) is thicker than cooler oil (40C). I'm not sure how thick the oil would be at ~20C (room temperature), but I would imagine it'd be thinner still than it would be at 40C, but I haven't seen anyone do such tests with viscosity-measuring machines. (Edited to my being incorrect.)

That said, I do my oil changes warm: helps avoid burns, yet still has any contaminants mixed up with the oil.
 
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