Hot vs cold oil change video, long vs short drain time lapse.

[Owen Lucas]

Hopefully this video helps settle the debate between changing oil hot vs cold and how much extra oil you get out when you drain it for 12 hours.

I'm sure most BITOGs already knew the answer to this question but I thought it would be nice to see the different temp oils in action, especially with a 12 hr time lapse.

Definitely not a scientific method but I tried to eliminate variables as best I could to ensure the oil pan was as empty as possible before filling it up again for each change.

 

[Dave Hess]

I like to drain hot since I have a Fumoto valve on all my cars, very simple with no mess.

I figured the drained oil would be the same amount after 12 hours in video.

 

[Passport1]

Amazing display of scientific rigor to answer a question that is almost never asked.

 

[fsdork]

Interesting video. As you said, it's not totally scientific so it leaves a number of unanswered questions. It seems the cold test scenario may be a bit misleading (not suggesting that was the intent) due to the methodology. I wonder how a third scenario would play out whereby you let the vehicle rest for a day or more before beginning the drain. This would more accurately represent a DIY situation where the vehicle is sitting in the garage or driveway, and the owner starts the oil change process on a Sunday morning without starting the vehicle first. This would allow as much oil as reasonably possible to be in the pan at the start of the procedure.

 

[Owen Lucas]

Interesting video. As you said, it's not totally scientific so it leaves a number of unanswered questions. It seems the cold test scenario may be a bit misleading (not suggesting that was the intent) due to the methodology. I wonder how a third scenario would play out whereby you let the vehicle rest for a day or more before beginning the drain. This would more accurately represent a DIY situation where the vehicle is sitting in the garage or driveway, and the owner starts the oil change process on a Sunday morning without starting the vehicle first. This would allow as much oil as reasonably possible to be in the pan at the start of the procedure.

That's a good point, the vehicle did not sit overnight for the cold test, would be interesting to see.

I did put a borescope into the oil pan with an attempt to record the internals rotating for a few seconds when cranking with the fuel pump fuse pulled. A few more milliliters came out, maybe 5? I did not get that on camera externally though and the borescope recorder was acting up. Would have been a cool shot. Next time.

 

[Malo83]

I drain HOT, more stuff in suspension and quicker draining.

 

[Hall]

Maybe those that feel it's "better" to let the oil drain overnight in order to get what, an add'l ~150 ml out, will stop being so OCD ! That amount of oil is inconsequential.

 

[supton]

Interesting. I wonder: hot oil expands, so, more should come out, as it takes up more space--no oil drain is seemingly flush with the exact bottom of the pan, there seems to always be a lip, so some amount is left behind.

But going against my thought would be, if hot oil expands, then the fluid level in the beaker should have decreased as it reached room temp.

Oh well, regardless, my mind was made up before watching this and wasn't going to be changed. Done mine cold for years, not going to change now. 0Wx means I don't care what the temperature is: if it is warm enough for me to crawl under the car, the oil will flow just fine for a drain.

 

[Hall]

But going against my thought would be, if hot oil expands, then the fluid level in the beaker should have decreased as it reached room temp.

"Chemically" (??) or theoretically I'm sure that is true. In the real-world, using beakers with simple crude level markings, it's pretty much not measurable. I dealt with this a few times doing ATF drain and fills on my wife's Fusion (no dipstick). I drained it warm/hot and poured it into a 5L plastic bottle with 250ml increments. I marked the level with a Sharpie marker and let it sit. The temperature went from 140º F (approx, used an infrared temperature gun) and decreased to ambient temperature (60-70º F) with no visible change in level. I threw out the whole OCD-level thinking of hot vs cold and different volumes of liquid after I did this a 2nd time (just in case I did something off the first time).

 

[supton]

"Chemically" (??) or theoretically I'm sure that is true. In the real-world, using beakers with simple crude level markings, it's pretty much not measurable. I dealt with this a few times doing ATF drain and fills on my wife's Fusion (no dipstick). I drained it warm/hot and poured it into a 5L plastic bottle with 250ml increments. I marked the level with a Sharpie marker and let it sit. The temperature went from 140º F (approx, used an infrared temperature gun) and decreased to ambient temperature (60-70º F) with no visible change in level. I threw out the whole OCD-level thinking of hot vs cold and different volumes of liquid after I did this a 2nd time (just in case I did something off the first time).

You'd swear, this couldn't be true, given all the verbiage and dire warnings about having the transmission within a 3 degree window to properly check the fluid level... forget what the temperature window was on my Tundra, but it was not very wide. Maybe it matters over gallons not a gallon, dunno.

 

[simple_gifts]

Maybe those that feel it's "better" to let the oil drain overnight in order to get what, an add'l ~150 ml out, will stop being so OCD ! That amount of oil is inconsequential.

Right, leaps of faith to assume getting more oil out is actually consequential, which it probably isn't.

"Minutes before" the oil was properly lubricating and protecting the engine; the moment the owner decides to change it, it suddenly is detrimental?

 

[JeffKeryk]

If I am swapping the filter, I prefer cooler. With the MityVac, the hotter the better.
Regardless, just service it at 5K intervals and your engine will be happy.

 

[Passport1]

"Minutes before" the oil was properly lubricating and protecting the engine; the moment the owner decides to change it, it suddenly is detrimental?

Good point. Must be the DIY BITOG types are a fickle bunch.

 

[carviewsonic]

I changed oil and filter on the Honda a few days ago. Cold start in the driveway, and the engine oil pan was warm but not hot by the time it was up on the ramps in the garage. Drained until dripping, installed plug. Good enough. Don’t want to take all day to do an oil change.
It took 4.2 litres with the filter, same amount as the manual says it should take.

 

[Hyundai Respecter]

I usually change it on a cold engine that sits overnight. I let it drain 10-15 mins or so while I do other things like check the air filter, air the tires, wipe down the plastics in the engine compartment. Most of it drains out, and that’s good enough for me.

 

[4WD]

 

[ATex7239]

So at 15-20 mins, which is a fairly reasonable and common amount of time to allow for draining, the difference was 10-20 ml. This translates to .02 qt or less. And it would take approximately half a day of draining to double that amount. Even at the highest differential point of around 50-60 ml at 1-3 hours that only translates to approximately. 06 qt or less.

These figures are what I would call statistically insignificant. Continuing to cold drain as always.

 

[BHopkins]

Owen, thanks for going to the effort for this experiment. It would be interesting to see "cold" drain, at closer to 20°C - 22°C oil temperature, would compare.

It has always been interesting to me how many people will spend a very long time, hours, sometimes even overnight, waiting for the last drops of oil, but ignore how much oil stays in an engine. Short of doing a full teardown, there is no way to get all the oil out of an engine. Of course the amount of oil remaining in an engine isn't just a few ounces either. In the case of many engines, it is over a quart. So as soon as you pour fresh oil into an engine, and run it for a few seconds, your fresh oil is mixed with dirty oil. Perhaps around a 8:1 ratio, fresh to dirty?

So how much value is there to wait, beyond say when the oil goes from a small stream to a drip, when draining oil?

 

[ATex7239]

Owen, thanks for going to the effort for this experiment. It would be interesting to see "cold" drain, at closer to 20°C - 22°C oil temperature, would compare.

It has always been interesting to me how many people will spend a very long time, hours, sometimes even overnight, waiting for the last drops of oil, but ignore how much oil stays in an engine. Short of doing a full teardown, there is no way to get all the oil out of an engine. Of course the amount of oil remaining in an engine isn't just a few ounces either. In the case of many engines, it is over a quart. So as soon as you pour fresh oil into an engine, and run it for a few seconds, your fresh oil is mixed with dirty oil. Perhaps around a 8:1 ratio, fresh to dirty?

So how much value is there to wait, beyond say when the oil goes from a small stream to a drip, when draining oil?

There appears to be little value if any. The longest drain time yielded an additional 150 ml which equates to approximately .15 qt. Running a filter for more than one OCI will leave as much ( or more ) oil in the engine as a 15 min cold drain. I think based on the findings of this video the answer to the hot vs cold or short vs long drain debate is basically do whatever you want cause it doesn’t really matter.

 

[TheLawnRanger]

Warm enough to drain well, cool enough not to scorch my hands.