Hot vs cold oil change observation..

[rcy]

Normally, I'm a hot oil change guy. I change the oil after driving. My most recent oil change I did after the car sat overnight.

When removing the oil filter in a hot oil change, a substantial amount of oil runs out (some from the filter, but I think a fair amount from inside the engine).

I noticed with the cold oil change that nothing ran out from inside the engine when I removed the oil filter. There was some oil in the filter, but not as much as when doing a hot oil change.

Is this to be expected, or has all the oil drained past the anti-drainback valve in the filter (or is it normal for oil to do that anyway after the vehicle had sat for a while).

The vehicle in question is a 2006 Lexus RX400h. The filter was the Toyota filter.

 

[AuthorEditor]

The filters I use, mostly PureOne and Motorcraft, seem to hold a good load of oil for a long time. Certainly, leaving the car overnight will not let all the oil drain out of the filter. I've left some filters draining hole side down for months over the winter and they still retained oil when I opened them in the spring--quite a mess because I wasn't expecting so much retained oil! This is one reason why better filters have silicone ADBVs.

 

[Schmoe]

Letting it sit is going to let it all drain via gravity, and that takes time. When you go it when it's still hot and just got done driving, there's going to be a lot of oil still coating the engine block and every surface inside.

 

[Artem]

I personally don't like doing oil changes on a cold engine because the cold/dry start afterward is

I'm experimented with this on my 98 Camry V6. During a cold start after changing the oil, the valvetrain is EXTREMELY LOUD for quite a long time (what seems like forever) until oil finally reaches the top and starts lubricating.

With a warm engine, there is still a good enough film of oil on the internals so it doesn't sound as bad and stops chattering within a few seconds.

Obviously more oil will drain out if left to stand overnight but its just not worth it to me, in fear of extra wear because of lack of lube during the initial start.

my $0.02

 

[rcy]

The cold/dry start afterwards? How is that any different than just starting the engine after it's sat all night anyway?

Aside from the fact that the new filter will be empty unless you prefill (which I do), the rest of the engine will be the same after a drain/refill as after sitting all night, no?

Like I said, I'm usually a hot changer, but the lack of mess when I removed the filter is very enticing..

 

[901Memphis]

I park my car on my ramps the night before and its cold when i drain it. I can't fit under it otherwise.

I have never had any noise from draining the oil cold and i would rather get all the old dirty stuff out and hope there is still a film on the parts enough to keep it until the oil pressure gets back to normal.

If you fill the oil filter properly before installing i don't see much of a chance of the engine going without oil?

 

[uart]

Originally Posted By: Artem
I personally don't like doing oil changes on a cold engine because the cold/dry start afterward is

I'm experimented with this on my 98 Camry V6. During a cold start after changing the oil, the valvetrain is EXTREMELY LOUD for quite a long time (what seems like forever) until oil finally reaches the top and starts lubricating.

With a warm engine, there is still a good enough film of oil on the internals so it doesn't sound as bad and stops chattering within a few seconds.

Obviously more oil will drain out if left to stand overnight but its just not worth it to me, in fear of extra wear because of lack of lube during the initial start.

my $0.02
+1

It varies from one car to the next so I'm not surprised that not everyone has experienced it, but certainly I've had some cars that sounded pretty awful on the first cold start after an oil and filter change. So now I always like to do warm changes, nice and quick, no mucking about and get it restarted as soon as possible. I don't give a dam if I could have got another cup or so more old oil out of it if I'd let it drain longer.

Here's my procedure.

1. If starting with a cold engine I warm it up, but only for about 5 minutes. I want the oil all throughout the engine and I want it just warm, not scolding.

2. Stop the engine and immediately remove drain plug (and filler cap) and let it start draining.

3. Remove the old filter, pre-fill new filter and install.

4. Replace drain plug and fill with fresh oil. It probably only drains for 10 minutes which is the time I spend mucking around with filter etc. Like I said I don't give a dam that there's a little bit of oil in there still draining back from where it's doing it's job, I'm actually glad about it.

5. Start the engine straight away while it's still a little warm. Run for just 30 seconds then turn off and let it settle for a the time it takes me to pack up my tools etc.

6. Recheck levels and if necessary add oil to get it within about 1/8" of the top level on the dipstick and I'm done.

 

[Eddie]

I like doing warm oil changes after a full warm up by driving. I let the vehicle set for 1/2-3/4 hour and then drain the very warm oil. A compromise for sure but, this has worked for me for 50 years and I don't get scalded

 

[shrooms]

Originally Posted By: Eddie
I like doing warm oil changes after a full warm up by driving. I let the vehicle set for 1/2-3/4 hour and then drain the very warm oil. A compromise for sure but, this has worked for me for 50 years and I don't get scalded


Using a Fumoto drain valve, you could drain without scalding.

 

[demarpaint]

I've done a few cold oil changes over the years, but was taught in auto shop back in the 70's that changing the oil after the engine was warmed up was the proper way to do it. So I take the car for a short drive, put it on the ramps and drop the oil. I do some yard work or clean up the garage and let it drain for about an hour, drop the filter, pre-fill the new filter and complete the oil change. I'm happy with the method I use. If I was doing 25,000 mile oil changes I might be a little more worried about trying to squeeze that extra pint of spent oil out of my engine, but for the OCI's I do I don't worry much about it. Besides I change my filter each OCI and I'm sure that gets more dirty oil out of an engine than changing oil cold or letting it drain overnight. JMO

 

[ZZman]

I thought getting scalded by the hot oil was part of the manliness of doing the oil changes. huh........

Anyway......I always do mine either after driving or after a 10-15 minute warm up.

 

[rclint]

I don't think it matters one bit if a hot or cold oil change is done, nor the short term noise that occurs afterward. Also filling of not filling the oil filter in any combination of the above it just will not make any difference to the engine. Advantages, and disadvantages of each way have good points, but still it will not make any difference to the engine.. the sounds a engine can make does make us curl our toes LOL.

 

[RamFan]

I normally let the engine run for a 2-3 minutes but that is just the way I was taught and it kind of gets stuck with you, ya know? In all honesty though I don't see the difference between a cold change and a warm change.

If you change it cold and start it up to circulate the oil, I don't see how that is any different if you were just getting in your car and start it up to drive somewhere. The engine is in the same state of dryness either way so I don't see harm being done by a cold change. Like wise I don't see any real benefit of a warm change. Unless the reason I was taught is true...

How I was taught was that letting the oil circulate for 5 minutes would allow for any debris that was in the oil to lift off of the surfaces (Whether it was in the pan or on a wall surface somewhere in the engine) so that when the drain plug was removed more of the debris was in suspension thus removing more debris from the engine.

Anyone believe this as well?

 

[PF52]

Originally Posted By: Eddie
I like doing warm oil changes after a full warm up by driving. I let the vehicle set for 1/2-3/4 hour and then drain the very warm oil. A compromise for sure but, this has worked for me for 50 years and I don't get scalded


I do it exactly the same way. I don't think its a compromise; you're still draining it "hot", just not quite as hot as it would be immediately after shutting off the engine.

 

[uart]

Originally Posted By: RamFan
If you change it cold and start it up to circulate the oil, I don't see how that is any different if you were just getting in your car and start it up to drive somewhere. The engine is in the same state of dryness either way so I don't see harm being done by a cold change.

I'm not sure about that. Depending on how much oil you're able to pre-fill the filter with and also the design of the oil pump etc there's probably a few spaces filled with air that that would normally (normal cold start) still be filled with oil. Like I said it's not the same with every car, but I've certainly seen some cars that take longer to get good oil pressure on the first cold start after a cold oil change.

Quote:
How I was taught was that letting the oil circulate for 5 minutes would allow for any debris that was in the oil to lift off of the surfaces (Whether it was in the pan or on a wall surface somewhere in the engine) so that when the drain plug was removed more of the debris was in suspension thus removing more debris from the engine.

Anyone believe this as well?


There might be something in it. I like to circulate the oil just before a change mostly so that I know that there's lots of oil still clinging around the engine when I restart it after a quick warm change.

 

[VWguy]

The industry standard is probably to drain the oil warm/hot. Since most manufacturers support there dealers and personal experience at independent shops have taught me to first road test the vehicle to verify any issues. It is my belief that this procedure benefits the car owner, shop owner, and the technician. Specific jobs on the rest of the vehicle could modify this standard practice.

 

[steve20]

I'm the hot oil type, prefill the filter an immediate warm restart.
The only thing I do not get is why all of you seem to drain the oil first, and then with a full pan of used oil mess with the filter at that point?
I always go after the filter first, so if it slips, or it is too hot and I happen to drop it, it drops in an EMPTY pan

Steve