Any benefit to changing oil when engine is warm???

[91344George]

Cold..

As long as the car was driven for a period of time the night before it was parked to get it up to operating temperature.

Drain stone cold. The nice thing is that when removing the oil filter you don't get any oil flowing out of the filter all over the place. Also you don't burn your hands and arms.

 

[45ACP]

Originally Posted By: LeakySeals
Originally Posted By: SteveSRT8
The whole change it warm thing is to have the engine well lubricated for the dry restart. Most people put the filter on empty and thus you wait a few seconds for oil pressure.


Always prime the new filter media so so there is a balance of pressure inside the filter.


I have seen mechanic add 3 or 4 quarts of oil, put engine cap back on, crank engine for 5-10 seconds, and put in the last quart. Is that a good way to do that, and is that why that is done?

 

[mechtech2]

A cold drain allows previously hot oil to fully drain in to the pan.

 

[Artem]

So many opinions in here, wow.


Originally Posted By: 45ACP
Originally Posted By: LeakySeals
Originally Posted By: SteveSRT8
The whole change it warm thing is to have the engine well lubricated for the dry restart. Most people put the filter on empty and thus you wait a few seconds for oil pressure.


Always prime the new filter media so so there is a balance of pressure inside the filter.


I have seen mechanic add 3 or 4 quarts of oil, put engine cap back on, crank engine for 5-10 seconds, and put in the last quart. Is that a good way to do that, and is that why that is done?


I see no reason to not dump the other quart unless you're not sure of the proper amount the engine needs and don't want to overfill.

 

[LeakySeals]

The best way to drain oil is hot. I tested to figure it out. Try it yourself using 2 plastic gallon milk or spring water jugs.

Test 1) - Transfer hot waste oil from the drain pan to the 1st plastic gallon jug immediately. Transfer hot waste oil from the 1st gallon jug to a 2nd gallon jug immediately. In my test all oil transferred.

Test 2) - Wait 5 hours or next day, transfer cold waste oil from the 2nd gallon jug back to the 1st gallon jug. In my test the bottom of the 2nd jug was coated with heavy dark oil that did not transfer. Even after repeated shaking a small amount remained stuck to the bottom.

 

[LeakySeals]

Originally Posted By: 45ACP
Originally Posted By: LeakySeals
Originally Posted By: SteveSRT8
The whole change it warm thing is to have the engine well lubricated for the dry restart. Most people put the filter on empty and thus you wait a few seconds for oil pressure.


Always prime the new filter media so so there is a balance of pressure inside the filter.


I have seen mechanic add 3 or 4 quarts of oil, put engine cap back on, crank engine for 5-10 seconds, and put in the last quart. Is that a good way to do that, and is that why that is done?


The cranking without starting was to prime the filter and cut down on the dry start. Not sure why the last quart was delayed unless he wasnt sure of the capacity. I can't find it right now, but there is a video of 2 identical filters cut open. One primed, one unprimed. The unprimed filter had collapsed wavy media. The primed filter was fine. Video was about why to prime a filter/what the initial surge of oil into the dry media can do... Not sure its true, but I've been priming manually ever since. Its not hard.

 

[ltslimjim]

Originally Posted By: 91344George
Cold..

As long as the car was driven for a period of time the night before it was parked to get it up to operating temperature.

Drain stone cold. The nice thing is that when removing the oil filter you don't get any oil flowing out of the filter all over the place. Also you don't burn your hands and arms.

Originally Posted By: mechtech2
A cold drain allows previously hot oil to fully drain in to the pan.


Combine these two and I would choose to drain cold when possible. The problem is I'd have to park on ramps over night.

 

[45ACP]

Originally Posted By: ltslimjim
Originally Posted By: 91344George
Cold..

As long as the car was driven for a period of time the night before it was parked to get it up to operating temperature.

Drain stone cold. The nice thing is that when removing the oil filter you don't get any oil flowing out of the filter all over the place. Also you don't burn your hands and arms.

Originally Posted By: mechtech2
A cold drain allows previously hot oil to fully drain in to the pan.


Combine these two and I would choose to drain cold when possible. The problem is I'd have to park on ramps over night.

If the oil was drained when perhaps came in from work (hot) and left to drain overnight, it would accomplish suspended contaminants draining more freely from hot oil AND the hot oil cooling, into the pan with plug removed, ready for fresh fill in the morning/cold.

Not sure who has that patience anymore, however.

All in all, it is NOT a noticeable amount difference between hot/cold drain, if you let it drain until the slow stream turned to a fast drip and then ~5 more minutes to a slow drip anything beyond that is just nit-picking.

It should also be noted that when the engines were cranked (with the key) they always ended up starting so my mechanic just let the car run for a few seconds before turning it back off. He also mentioned the "get it flowing through the filter, its hot oil" reason. I thought it was a potentially unnecessary step, but i devised a method to incorporate that and fill half the oil capacity, bolt and filter installed, let it run for a few seconds, fill the rest. Perhaps overkill but.. i do use cheap filters..

How recently was that video and what car and filter was it with the primed and unprimed side by side? And do cars really need oil filters primed nowadays?

 

[Artem]

Originally Posted By: LeakySeals
The best way to drain oil is hot. I tested to figure it out. Try it yourself using 2 plastic gallon milk or spring water jugs.

Test 1) - Transfer hot waste oil from the drain pan to the 1st plastic gallon jug immediately. Transfer hot waste oil from the 1st gallon jug to a 2nd gallon jug immediately. In my test all oil transferred.

Test 2) - Wait 5 hours or next day, transfer cold waste oil from the 2nd gallon jug back to the 1st gallon jug. In my test the bottom of the 2nd jug was coated with heavy dark oil that did not transfer. Even after repeated shaking a small amount remained stuck to the bottom.


Good stuff LeakySeals.

 

[Artem]

Originally Posted By: 45ACP


How recently was that video and what car and filter was it with the primed and unprimed side by side? And do cars really need oil filters primed nowadays?


It doesn't matter how long ago the engine was built, the oil filter works the same and it WILL benefit from priming.

In my 98 Camry V6, the oil filter mounts almost upside down.
I still prime it by filling it up to the top. Within seconds, all the oil soaks into the filter media and it's ready to be put on.
The oil pressure light goes off much quicker if the oil filter is primed.

 

[DavidZ28]

Originally Posted By: Danh
Hot. Not only does oil flow out faster, but the hot engine heats the new oil so it circulates, fills the new filter and builds oil pressure more quickly.


Good point, never thought of that before!

 

[whizbyu]

This may be bordering on obsessive compulsive behavior, but I drain my oil hot, remove the oil filter, suck out the bottom on the filter cradle with an old baster to get the oil out, put the oil cap on without the new filter, leave the drain plug OFF, remove the oil cap at the top, and blow compressed air into the oil cap with rags to act as a seal. Makes a mess at the drain plug site but I have a large pan from an old kennel to catch the "oil spray".
This gets an extra cup or so out of the engine.

 

[The Critic]

Originally Posted By: Pop_Rivit
In my opinion, no, there's no benefit to changing it hot.

If there is significant debris in the oil you have a bigger problem than an oil change will fix.


+1

 

[DragRace]

Warm or hot,oil will drain faster.

Cold,it just takes longer for the oil to drain.

Either method you choose,there's always leftover oil in the motor.Pick a method and dont lose sleep at night over it.

 

[VNTS]

That is my opinion, more has drained into the pan that way, less hung up.

I dont thing it really matters though, done it cold for 35 yrs, never had any issues!

Originally Posted By: garlicbreadman
cold all the way..gets more out than hot.

 

[Bgallagher]

Originally Posted By: DragRace
Warm or hot,oil will drain faster.

Cold,it just takes longer for the oil to drain.

Either method you choose,there's always leftover oil in the motor.Pick a method and dont lose sleep at night over it.


+1 I always warm up the vehicle for about 5 minutes before I drain it. Just makes it quicker.

 

[Maxima97]

When oil is warm, the dirt is still suspend in oil and oil flow fast. I can pretty get oil change in 10 min. I will let car cool down at 30 min not to burn my hand.

 

[Kestas]

I developed a workaround so you don't burn yourself while draining it hot.

Remove oil filter first. Let it drop into the drain pan. Install new filter.
Move drain pan under oil pan. Remove drain plug and let it drop into drain pan.
After most of the oil is drained, move a smaller drain pan (I use an old cut open quart container) in place to catch the last bits of oil.
Empty drain pan of used oil and fish out the plug.

 

[Maxima97]

Originally Posted By: Kestas
I developed a workaround so you don't burn yourself while draining it hot.

Remove oil filter first. Let it drop into the drain pan. Install new filter.
Move drain pan under oil pan. Remove drain plug and let it drop into drain pan.
After most of the oil is drained, move a smaller drain pan (I use an old cut open quart container) in place to catch the last bits of oil.
Empty drain pan of used oil and fish out the plug.

The filter has 1/2 Qt oil inside, I will drain the oil 1st and then twist the dirty can. My Ford Explorer is the most hard to twist the can: there is a lower control arm right under the can and black oil will pour right on to the LCA then into the pan. The dealer has a oil collector get diret under the can.

 

[Artem]

Originally Posted By: garlicbreadman
cold all the way..gets more out than hot.


Originally Posted By: VNTS
That is my opinion, more has drained into the pan that way, less hung up.

I dont thing it really matters though, done it cold for 35 yrs, never had any issues!

Originally Posted By: garlicbreadman
cold all the way..gets more out than hot.


Have you ever measured the amount of oil that "drains into the pan" as the engine cools overnight? I did.

I did a 30 minute oil change, waiting until the draining oil has come to a very slow drip. I then put the drain plug back in and went to bed. The next morning, I put a clear plastic cut under the drain plug and removed it. Guess how much drained out? 2/10th of a cup! and that's from a 3.0L V6 in my 98 Camry. I'm sure the tiny 4 cylinder engines would produce less oil drainage as the engine cools.

I also did the test of pouring hot engine oil from clear bottle to clear bottle, as someone else mentioned. The hot oil didn't leave much, if anything on the bottom of the bottle after sitting for an hour, cooling off. As it got cold overnight though, it left a bunch of stuff stuck to the bottom of the bottle.

I also notice this with a lot of the jugs of used oil that I take to the dump. Once i drain out the cold oil, there's a black film left at the bottom of the jug. Warm oil from a recent oil change leaves the jug sparkling clean.

Those who think MASSIVE amounts of oil remains glued to the engine internals after you shut down the engine and it requires 12+ hours of sitting to settle into the oil pan are WRONG! 99% of the oil that can drain down into the pan, does so within 10-15 minutes of shutting down the engine. Waiting for 0.1% from a small portion of film that is still draining down is hilarious to me. There's still a good half a quart+ of old oil stuck in the engine passageways. Are you going to tilt the engine side to side, forward and backwards to try to drain the rest of the oil that is still in the engine? Come on now...

As to the lack of "issues" you didn't have while doing your OCs this way... What issues? LOL. How can you possible measure the effects of all those DRY starts in the morning, after you drained the remaining 1/4th cup of oil that was on the surface of the engine's internals?