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Change oil cold or warm- which is better?

restorer-john

restorer-john

Addicted Member
Forgive me if this is a dumb question, but is it better to drain & change oil when the engine is cold (normal 25 degrees C) and all at the bottom of the engine (more likely to get it all out?) or when the engine is warm (not hot as I don't want to get burnt undoing the filter and drain plug) so it 'flows' more freely out of the engine?

I can see benefits each way. What do you experts do?
 
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I'm no expert, but I've always performed this maintenance with the engine at operating temp. I can't imagine the minute amount of dirty oil left from this could be problematic, especially with a filter change at the same time.
 
I've always done it warm.

I guess it goes quicker.

In the old days, the old engines, having the oil warm are stirred should flush out more particles since they are still in suspension.

A cold engine has had time to drain down and they would be less oil still coating moving parts so when you start the engine, waiting for the oil to reach all the oil points would mean longer wear with low to no oil.

I don't think it really matters as long as you don't wait to do it every 20000-40000 miles.
(YES some people never change the oil)
 
Warm. Oil is thinner, and flows easier. Take the car for a drive, put it up on stands or ramps, then make yourself a cup of tea or coffee. That should give everything a chance to cool down enough to not burn your hands. I don't know if anyone else does it, but find out how to crank your car without it firing, in order to get the new oil circulated. On my Merkur, if you try and start it with your foot to the floor, it won't. On older cars, take a wire off the distributor. Newer cars might not like that though, or they may have coils on each plug.

Lee.
 
It's always warm/hot oil when I pull into the Quick Lube joint. For the money, I think the fast oil change places are a bargain. I can't get all the stuff together to do a driveway oil change for less time/money than they charge.

Oh...and full synthetic is the only oil for a civilized human being. You can argue all you want about tubes vs. solid state, but in oil world, Mobil One is King.
 
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I do mine warm/hot. My rigs are mostly used for relatively short drives. So, after a longer drive to burn off the condensation, I shut it down, let it cool down a bit then drain while still quite warm, but not scalding hot.
 
I've always done it warm. You don't ever want to have a plug wire pulled when you start a newer car. It can damage very expensive coil systems. The thinner oils you should be using will circulate so quickly any sort of pumping shouldn't be necessary. In the past I've used a power drill down the distributor hole to drive the oil pump, but that only works on some engines. Mobil One may be King, but Royal Purple is said to be Queen Bitch of the Universe.

Good oil site- https://bobistheoilguy.com/
 
Interesting, I must be old school then... always changed the oil when it was cold. Figured it was the best way to get most of the old oil out of the engine.

I was brought up that if the engine was ran, you wouldn't get all of the oil out that you could if it was cold. :idea:

I know the quick oil change places change it while the engine is warm, but if I don't change it, I have a local shop change it.
 
SPL db said:
Interesting, I must be old school then... always changed the oil when it was cold. Figured it was the best way to get most of the old oil out of the engine.

I was brought up that if the engine was ran, you wouldn't get all of the oil out that you could if it was cold. :idea:

I know the quick oil change places change it while the engine is warm, but if I don't change it, I have a local shop change it.
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It drains back rather quickly when warm. I do my own so it doesn't bother me at all to leave it drain the 5 extra minutes or whatever it takes for the stream to subside and subsequent dripping to stop.
 
Always do it hot, if there's any contaminants in the oil they'll be more likely to be suspended/dissolved than when cold. Kind of irrelevant with modern clean engines and synthetic oil, but old habits die hard.
 
I've always done it warm. Get it warm to thin it out, and circulate whatever crud is in there. Even if I drive enough to get up to full operating temps, I can just let it sit until it gets to the point of not burning my hands. It also doesn't take all that long for all of the oil to return to the pan (unless you've got some really clogged oil ports up top).

Synthetic is the best way to go--it doesn't degrade like conventional dino oils. New cars factory equipped with synthetics are now recommending 5K or even 10K oil change intervals--I'm "old school", but I use a method learned from an old Taxi mechanic--use the best oil you can buy, change the filter only at 3K and just top it off, and then do a full oil and filter change at the next 3K interval--has worked for me for years. The important thing is to keep the oil clean and full. Most people don't realize how much engine oil factors into heat dissipation as well as lubrication, so keeping it full is important.

You will NEVER see one of my vehicles at one of those "Qwiky Lube" places. Those guys are mainly half-trained monkeys making barely over minimum wage, and the manager's job is to sell you $50 wiper blades to go with your $20 oil change.
 
savatage1973 said:
I've always done it warm. Get it warm to thin it out, and circulate whatever crud is in there. Even if I drive enough to get up to full operating temps, I can just let it sit until it gets to the point of not burning my hands. It also doesn't take all that long for all of the oil to return to the pan (unless you've got some really clogged oil ports up top).

Synthetic is the best way to go--it doesn't degrade like conventional dino oils. New cars factory equipped with synthetics are now recommending 5K or even 10K oil change intervals--I'm "old school", but I use a method learned from an old Taxi mechanic--use the best oil you can buy, change the filter only at 3K and just top it off, and then do a full oil and filter change at the next 3K interval--has worked for me for years. The important thing is to keep the oil clean and full. Most people don't realize how much engine oil factors into heat dissipation as well as lubrication, so keeping it full is important.

You will NEVER see one of my vehicles at one of those "Qwiky Lube" places. Those guys are mainly half-trained monkeys making barely over minimum wage, and the manager's job is to sell you $50 wiper blades to go with your $20 oil change.
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The half-trained monkeys that change my oil are two young sisters that own their franchise, and take it damn seriously. Extremely professional, competent and they've never tried to sell my anything at all. I drive a lot, and sometimes will get an oil change when I'm away from home, and have never had a bad experience at any of the major players. YMMV, of course, but since you've NEVER used their services...well, you know. Sure, you've heard all the stories about the drain plug, etc., but for the most part these small businesses are pretty well run.
As for your taxi mechanic's method, that sounds like it would work pretty well so long as you had a 60 year old car with an oil canister located topside that could be easily opened, remove the filter, drop in a new one and screw the cap down. But I can't see how the heck you'd do it on most modern cars?
I'm know Amsol sells an entire kit that essentially adds a 2nd filter canister that gives the ability to change a filter cartridge.
 
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Todd Dodds said:
The half-trained monkeys that change my oil are two young sisters that own their franchise, and take it damn seriously. Extremely professional, competent and they've never tried to sell my anything at all.
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That is a whole different scenario--they are like a local garage, and a "family business"--so they have a vested interest in doing quality work and keeping customers happy, so they will come back. The ones in my neck of the woods are owned by God knows who, and the managers are pressured to sell overpriced accessories or additional services like tranny flushes, coolant flushes, wiper blades, etc, and meet "quotas" of cars serviced per day, and they just "crank 'em out" to meet numbers, and the employees are poorly paid, so not so interested in quality--they clock in and clock out and collect their meager paychecks.

My local mechanic that I use owns his own business, and I totally trust him. But again, he has a vested interest in the quality of work coming out of his garage--this is what pays his mortgage and is putting his kids through college.

I own my own construction company--so I know. If I build you a deck, re-paint your house, re-finish your hardwood floors, etc, you will tell your neighbors and friends--I have to do a good job, because word of mouth is the best advertising you can get. There are many tines we have done multiple jobs for the same company or in the same neighborhood just due the putting out a quality product/service.
 
leesonic said:
On my Merkur, if you try and start it with your foot to the floor, it won't.
Lee.
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That is called a de-choke mode. Supposed to help clear fuel from the combustion chambers if the car is flooded.

We used to use that trick to check for leaking fuel injectors. If the car started in de-choke it usually had injectors that leaked during a not soak.

Is your Merkur an XR4TI ?
 
Todd Dodds said:
It's always warm/hot oil when I pull into the Quick Lube joint. For the money, I think the fast oil change places are a bargain. I can't get all the stuff together to do a driveway oil change for less time/money than they charge.

Oh...and full synthetic is the only oil for a civilized human being. You can argue all you want about tubes vs. solid state, but in oil world, Mobil One is King.
Click to expand...

I'll never patronize one of those quick lube places. The last time I did was something like 20 years ago because I didn't have time to do it myself and for some reason the little garage across the street from work was booked up, and I was leaving for a 5 hour road trip the next day. The idiots at Jiffy Lube filled my windshield washer bottle with water as a "courtesy" meaning I had to drive over the Appalachians with no windshield washers, and had to find a VW dealer that was open on Christmas Eve to buy a replacement little grommet for the washer pump because the old original disintegrated when I pulled the bottle to thaw it after I got to my destination.
 
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