Oil change on cold engine

[AldeanFan]

My dad insists that you have to change oil with the engine hot.

Normally I would but my ‘54 Country Squire is already on stands in the garage and has been sitting all winter.

To me it makes sense to change the oil while it’s up in the air already and all the oil is sitting in the pan. It’s in a spot I can’t run it to temp without moving it.
My dad insists that I put the wheels back on, back it out or drive it till it’s up to temp, then change the oil with the engine hot.

Since I’m on lockdown and have nothing else to discuss, what’s your opinion?


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[sberry]

Just drain it, it's already all down in the pan. I change cold all the time. It doesn't know the difference.

 

[Millwrong]

I prefer to do it warm because the oil is a little thinner and comes out quicker, and because a good deal more of the contaminants will still be in suspension. Its certainly ok to do it on a cold engine, but there may be some stuff on the bottom of the oil pan that doesn't come out. If you really don't want to take it for a drive, change the oil as-is. Since you're on lock-down however, why not spend the time and take it for a rip??

 

[Chad M]

Maybe you could figure out how to warm the oil pan, before you drain the oil. It might get a few more of the particles flowing that had settled on the bottom.

 

[dagofast]

Yeah, just change it. Cold oil will drain slower, but most of us having nothing but time now, right?

 

[bwringer]

I hate working on hot engines.

Changing oil hot or cold doesn't make an iota of difference to the engine, but it does make a difference to you because maybe you won't burn your arm on hot exhaust or burn your fingers.

You'll also need to give the oil an extra minute or two to stop dripping if you care deeply about removing that last .5 ounce of oil.

I think this is just one of those outdated mechanical urban legends left over from Ye Olden Dayes before oil filters and detergent oils.

Kinda like the stupid old saw about how concrete floors somehow magically drain batteries.

 

[Copymutt]

Minor point. If its synthetic, you'll get more drain flow cold than dino oil.

 

[Raisedonadeere]

It will drain slow off the bottom pan but time will take care of that, for instance over night will get as much out as would have come anyway. It is a nice thought to picture in ones head all the unsettled dirt flowing out with the hot oil but extremely minor consideration in my opinion in a situation like yours. There is probably not much of that anyway and it would still be there, if there is any, even after a short engine warm up drive. I would rather start that engine with fresh oil than stir up all the acids and other stuff that develops over time and flow that stuff everywhere.

As far as the car is concerned do what ever you want, but you still want to get along with your father. It is not going to kill you to humor him.

 

[sberry]

I dont like burned either. I change cold a lot cause its usually a side point or is really in for other service and happens to get the oil changed if its over due.
I agree with getting along with Dad but the engine wont know a difference. If this is something I was fixing, collecting, gonna keep and store etc an oil change cant hurt.
Start out at a known point. The oil you put in wasn't even invented when that car was new. I got a bunch of stuff that is on its lifetime oil changes. Some will never get a change unless it involved related work. Only problem I ever had and in recent history was an itty bitty pinhole in a filter super localized. Started dripping right thru it. It was a Wix but really old, was on there a long time. That was 10 yrs ago, I stop changed and put a new filter on.
Speaking of this I do have one seasonal I need to do in a ****** Dodge V6 that has ****** gasket stuff and **** timing chain design. It was junk when I do the intake and front. had some stuff on the vapor system clogged right up. Was a lack of maint on our part really, we drove it a long time and never give it a fussy tune up. Just missed it in an old truck. I don't even want to know what the bottom end looks like. I cant recall if we checked comp or not? It starts, runs, doesn't use or smoke. Ran it 2 hours yesterday.

 

[DGersic]

I do it both ways. If it has been sitting 24 hours or more, and I can do it in place, I’ll do it cold. If I have to start it, I’ll run it up to temp, and do it hot.


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[brownbagg]

there absolute no reason not to change on a cold engine, most of the contaminants are in the filter. just do it

 

[1redTA]

do it cold, just means you can have another beer while it is draining

 

[Farmerjonathan]

Will less likely strip the shoulders on a hot oil plug as it will come out easier when hot.

 

[jubilee]

Cold,I let it drain for a couple hours. Hot, I let it drain overnight. I almost refuse to pull the pan on an engine that has ran in the last 24 hours. Seems like every drop of oil that hasn’t found its way back to the pan on a recently ran engine ends up in my eyes

 

[finn]

The contaminants are bound to the oil molecules by the detergents and dispersants in the oil formulation. The only advantage to changing the oil while warm is that it flows better, so it takes less time to empty the sump.

That’s a pretty easy work around, though. Just wait an additional ten minutes before reinstalling the drain plug.

 

[GRivera]

One way to get around this issue is change the oil while still hot, at the time you store the vehicle for the winter. The fresh oil will survive just fine in the pan.

 

[ford33]

I change when the oil is cold. I don't like working on a hot engine.

My vehicles have run over 2 million miles combined and have no issues due to cold oil changes.

Just changing the oil frequently will be a benefit.

 

[BruceMc]

One way to get around this issue is change the oil while still hot, at the time you store the vehicle for the winter. The fresh oil will survive just fine in the pan.

And the thinking on that mostly is that it's better to store the engine with fresh oil, rather than leaving old oil along with any accumulated moisture or acids sitting in the pan over the winter.

 

[GRivera]

And the thinking on that mostly is that it's better to store the engine with fresh oil, rather than leaving old oil along with any accumulated moisture or acids sitting in the pan over the winter.

Yes, that is an added benefit for those of us with hobby cars. Two birds with one stone...

 

[joel63]

I hate working on hot engines.

Changing oil hot or cold doesn't make an iota of difference to the engine, but it does make a difference to you because maybe you won't burn your arm on hot exhaust or burn your fingers.

You'll also need to give the oil an extra minute or two to stop dripping if you care deeply about removing that last .5 ounce of oil.

I think this is just one of those outdated mechanical urban legends left over from Ye Olden Dayes before oil filters and detergent oils.

Kinda like the stupid old saw about how concrete floors somehow magically drain batteries.

Me too.

 

[lilredex]

Jack it up or let it down a little so the bottom of the pan slants toward the drain plug, then drain. Let it sit for an hour or so and add a cup or two of Varsol, that will flush out any remaining bits.

I prefer cold drains as everything is in the pan not hanging up on the head(s) somewhere.

 

[Pluribus]

If you're doing it cold, try to get as much oil into the filter before you put it on the engine. That way, when you start it, there's less lag for it to get to where it's needed. If the oil filter screws on vertically with the opening at the top, this is a piece of cake, and I fill that sucker up. If it's at an angle, then I'll put a bit less in it.

In general, I'm a fan of doing it when the engine is warm-ish but not hot. That way, there's still oil on most surfaces, and the lag for circulating oil is less on start up after the oil change.

 

[finn]

If you're doing it cold, try to get as much oil into the filter before you put it on the engine. That way, when you start it, there's less lag for it to get to where it's needed. If the oil filter screws on vertically with the opening at the top, this is a piece of cake, and I fill that sucker up. If it's at an angle, then I'll put a bit less in it.

In general, I'm a fan of doing it when the engine is warm-ish but not hot. That way, there's still oil on most surfaces, and the lag for circulating oil is less on start up after the oil change.

No modern manufacturer that I am aware of recommends filling either the oil filter or fuel filter when installing new filters.

You risk introducing dirt in your quest to “help” the engine on start up. It’s an uncontrollable intrusion that’s not a good general practice.

If you can find a current service manual that recommends this, please post it.

 

[JACDes]

The oil was HOT when you shut it down and parked it and now it is all sitting in the oil pan.

The only difference now is it could drain slower depending on the viscosity of the oil and the cold temp you are trying to change the oil. 40 degree and above you will not see any major difference.

 

[JACDes]

No modern manufacturer that I am aware of recommends filling either the oil filter or fuel filter when installing new filters.

You risk introducing dirt in your quest to “help” the engine on start up. It’s an uncontrollable intrusion that’s not a good general practice.

If you can find a current service manual that recommends this, please post it.

You also risk introducing dirt when adding oil to to the crank case via the valve cover filler....
And there a some people that can ruin an anvil with a rubber mallet...

No harm priming a new oil filter with clean oil and wiping some on the o-ring seal too.

 

[Tonyuk]

Back in the dark ages it helped the oil drain quicker since it improved the flow.

Now though it makes no difference.

I extract the oil, and have no issue with a warm or cold engine.

 

[czgunner]

It will take you 5 minutes longer. Big deal.
I prefer changing it cold when I have a choice, less chance getting burned.
You won’t ever get that last 1/4-1/2 quart of oil out of the engine whether hot or cold.

 

[SGKent]

I just did this last night. Pulled the car into the garage which stirs up anything. Went to the store to get the oil and filter since the oil change was one of those why didn't you tell me you put 8,000 miles on the car since the last change, and then drained it as soon as I got home. Changed the air filter and cabin filter while it drained, had a bite to eat, and then came out put the drain plug back in. Changed the oil filter, filled it and done. The only time one would want hot oil for sure is if non-detergent oil was being used, and in that case the oil galleries are probably like an old person with high cholesterol anyway. I used to work in a shop years ago, and when a 30's or 40's block came in it would take a day of cleaning to open up all the passages from the dirt that collected. Sometimes it would take a long steel rod cut into a drill bit on the end to get down the passage that stuff was so hard.

 

[sberry]

I just did one today. I thought I dad skipped oil service last year and it looks like I did. The note said fall of 17, really 2 full seasons and looks to be about 9k miles. . Looked nasty. Grease, check shocks, adjust rear brakes, inspect fronts, air in tires, **** lube, condition of rear bumper and hitch.

 

[Garett]

The only reason I wouldn't get the oil warm/hot is if its been sitting outside for months and months to years. Old cars may have lots of water in the pan under the oil.

If ther vehicle is regularly driven I will always get the oil at least warm if it isn't already hot.

 

[sberry]

It used to be common to see engine es with slime and sludge, today it's rare.

 

[Jeepster04]

Just curious, why cant you start it on the stands? I start vehicles all the time while theyre on stands, wheels or no wheels.

And I fill up filters as much as I cant also. Not really concerned what a manual says, sometimes its common sense. You can hear the valve train rattle like mad when you dont prime one.

 

[NYBODYMAN]

I've done hot, I've done cold. I don't think it makes much difference.

Please post pics of the Country Squire though!!!

 

[Pluribus]

No modern manufacturer that I am aware of recommends filling either the oil filter or fuel filter when installing new filters.

You risk introducing dirt in your quest to “help” the engine on start up. It’s an uncontrollable intrusion that’s not a good general practice.

If you can find a current service manual that recommends this, please post it.

Not sure if your objection is to contaminants in the new oil, or if you're referring to the danger of dirt somehow falling into the filter while putting new oil into it, so I'll address both scenarios.

1. Contaminants in new oil: This could be a legitimate argument, but I would rather err on the side of getting oil to an engine that hasn't run in a long time quicker vs. protect against whatever might be in new oil that needs to be filtered before it hits critical engine parts. I'm willing to be educated if there is information showing that new oil is destructive until it's filtered.

2. Dirt getting into filter during filling process: This would be operator error, and it is controllable. If there were any debris on the oil container I was using to add oil to the filter, I would clean it before doing this. That's what I'd do for pouring oil into the fill tube or valve cover on the engine as well. If your objection is here, I don't understand it, as there's very little different in the process than just putting a dry, empty filter on.

As for searching for a service manual that recommends pre-filling? I'm not sure if they even recommend oiling the filter's O-ring, but I do that every single time I change the oil too. If someone can explain why that's wrong also, I'm all ears.

 

[skulldrinker]

The rule book says looks like you'll have to drop the oil pan.

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[demarpaint]

I change my oil warm, after about a 20 minute ride, and a brief cool down. The contaminants are in suspension, and the oil drains faster. I leave the drain plug out for at least 30 minutes. I do other maintenance items to the car while I wait, or straighten out the garage or yard.

 

[Mikeske]

I just did my Ram 2500 Cummins engine yesterday and I did it after I had driven it to fully warm and then drained it and changed the filter. I only put oil in the filter about three quarters but I been doing it on vertical filters for the last forty plus years. Old habit that I have and sure you introduce debris in the filter but you can also do that if you don’t wipe off the oil filler cap before you take it off.

The main reason I do it on a warmer up engine it drains faster at least in my opinion. It also really doesn’t matter as far as I can see if it either cold or hot

 

[dsimatt]

I just did my Ram 2500 Cummins engine yesterday and I did it after I had driven it to fully warm and then drained it and changed the filter. I only put oil in the filter about three quarters but I been doing it on vertical filters for the last forty plus years. Old habit that I have and sure you introduce debris in the filter but you can also do that if you don’t wipe off the oil filler cap before you take it off.

The main reason I do it on a warmer up engine it drains faster at least in my opinion. It also really doesn’t matter as far as I can see if it either cold or hot

You're doing more potential for damage by prefilling the filter than having stuff fall in the oil fill as that will be filtered before it can get to bearings and such.

I always put filters on dry, might take 3/4 of a second longer to get oil pressure.

 

[samss]

No modern manufacturer that I am aware of recommends filling either the oil filter or fuel filter when installing new filters.

You risk introducing dirt in your quest to “help” the engine on start up. It’s an uncontrollable intrusion that’s not a good general practice.

If you can find a current service manual that recommends this, please post it.

From the Dodge FSM for my 2500 w/5.9 Cummins

INSTALLATION
(1) Fill the oil filter element with clean oil before
installation. Use the same type oil that will be used
in the engine.
(2) Apply a light film of lubricating oil to the seal-
ing surface before installing the filter.

 

[GRivera]

I change oil both hot and cold and doubt it makes a measurable difference. That being said, when hot the contaminants or any solids are in suspension, not sitting on the bottom of the pan or in other low areas where they like to collect, so theoretically they will drain out.