Hot or Cold oil change?

I do it whichever way is convenient at the time. I could see draining hot being a little more advantageous however I suspect that using high quality oil and filters and changing at reasonable intervals will have more impact on vehicle longevity than whether I drain hot or cold.
 
You do a oil change when it is cold and sat for a while, this way you can detect water in oil, it will settle to the bottom of oil pan.
 
I start the engine … idle a minute … on the ramps. Then I get my stuff ready. The oil is only a bit warm so not fully thinned like at OT. It has been circulated and likely being a bit thicker it holds contamination in suspension

I'm doing pretty much 5w30 or 0w20 … so it drains pretty fast in that state …
 
Originally Posted by fisher83
I do it whichever way is convenient at the time. I could see draining hot being a little more advantageous however I suspect that using high quality oil and filters and changing at reasonable intervals will have more impact on vehicle longevity than whether I drain hot or cold.

Yep. Same here.

I prefer hot but cold will be just fine.
 
On my V8's … it's a quart difference if you leave the filter on … that's in addition to whatever is trapped even with the filter off and no longer draining
 
I will drive around for at least 5 minutes before an oil change to get the contaminants in suspension. It also helps drain the oil more quickly when it is warmed up.
 
Originally Posted by Duffyjr
Originally Posted by PimTac
On the other hand, draining it hot also means stuff is suspended better so you might be getting more stuff out that would otherwise build up inside.

I have to ask where do the contaminants go when the oil is cold? As the engine cools and the oil drains back to the pan do the contaminants get left behind. Just trying to wrap my head around this because I don't change my oil any longer so when I take it to the quick lube the oil is warm but when I leave it with my mech it's usually the night before so I know he's not letting it warm up so if this is an issue I might consider going back to the quick lube.

I have said this several times here.
I don't understand the argument to change hot because of contaminates being suspended better. What contaminates?
Filters are there for a reason, to filter out contaminates (the size of them will vary depending on the filter, from 50 to 20 microns), and the oil holds whatever is left in suspension. Nothing to come out of solution.
If you have contaminates that you are worried about if changing oil hot vs cold, something else is majorly wrong with your engine.
Also, if changing hot, more oil is up in the upper parts of the engine still vs cold where everything has drained down already.
I do agree that warm oil does drain faster than cold, but not by much.
Hot or cold, it really makes no difference though over all.

I agree that 50 years ago, it may of made a difference. Just as running a qt of ATF in the engine 50 years ago was acceptable and helped clean due to the poor quality of oil and filtration then, but not today (even though you have many that say to do it still).

I change it cold because I don't like burning myself on hot oil or engine parts.
 
I'll add to your case … the 20-30 micron filter numbers you see here often are the high percentage ratings. Those same filters are taking out a decent percentage down to 12 microns or less … and likely at a rate faster than the engine produces the particles to start with.

Anything finer is staying in suspension …
 
Originally Posted by Vern_in_IL
You do a oil change when it is cold and sat for a while, this way you can detect water in oil, it will settle to the bottom of oil pan.

How much water would you need to have accumulated in the crankcase to actually see it draining out the drain plug?

Some moisture in the engine is normal and no cause for concern. It should burn off in normal driving.
 
Huge difference people.

It's not for the draining or the flushing, you change oil hot for the engine's sake alone. A warmed engine has oil all over so when you restart you don't go dry.

And since a significant amount of oil is still present in almost any engine after the draining why not get more of it out with a hot flushing drain...
 
In a couple hours … I'll pull the Tahoe up on one ramp to change the 0w20 … it was driven late yesterday …

What I will not do is burn my skin over this subjective debate …
 
Originally Posted by Railrust
I've always been told to do it when hot because the contaminants are held in suspension when the oil is hot, otherwise they settle on the bottom of the pan and the oil will flow right over it as it drains...leaving them in there. Don't know how much I agree with that, so I usually just do it when it's warm...I'm not into burning myself and having hot oil splash all over me.


Contaminants do not settle at the bottom of the oil pan, modern oils are designed to keep them in suspension.
 
Originally Posted by FordCapriDriver
Originally Posted by Railrust
I've always been told to do it when hot because the contaminants are held in suspension when the oil is hot, otherwise they settle on the bottom of the pan and the oil will flow right over it as it drains...leaving them in there. Don't know how much I agree with that, so I usually just do it when it's warm...I'm not into burning myself and having hot oil splash all over me.


Contaminants do not settle at the bottom of the oil pan, modern oils are designed to keep them in suspension.


Even so … higher viscosity suspends particulate better … so folks have a stir the pan logic going here … just think of all the valve cover shots we see here … why would the oil pan look worse unless you had a messed up engine that someone else abused. All of mine are over maintained … no worries
 
Mine gets changed warm. Mainly because I have to drive a mile down the road to where I do my change.
 
Originally Posted by krismoriah72
Since you fear contaminants on draining cold... you will cringe to know that there is nearly 1/2 to 1 qt of oil left in engine on a hot or cold drain.

I can tell you more is left in cold than hot. I always end up with more oil showing on the dip stick when I take it to my mech which I know he is changing it cold than the quick lube which is hot when I pull in, I'm guessing 1/2 quart more. This last change was worse since it was in the teens when he changed it, about a quart over. I'm almost tempted to run up to the quick change and ask them if they can drain some.
 
Last edited:
It could be a quart and not worried … I'm using high quality 0w20 and change around 6k …
What's left is good oil too … 8 quart system …
This stuff pours out of the jug like water anyway

I'm not changing SAE40 in Wyoming next February …
Varies case by case … Nobody has to agree one way or another …
 
Originally Posted by 4WD
It could be a quart and not worried … I'm using high quality 0w20 and change around 6k …
What's left is good oil too … 8 quart system …
This stuff pours out of the jug like water anyway

I'm not changing SAE40 in Wyoming next February …
Varies case by case … Nobody has to agree one way or another …




I did that once with SAE30 in below zero weather. Not fun at all. I used a milk can heater and surrounded the work area with a tarp to try and get the oil out easier.

Afterwards we bought a magnetic pan heater. It was a bit bass ackwards.
 
I hear you … Might have to work in cold places … but don't plan to live in one …
 
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