How much old oil is left in an engine after an oil change?

EF300 · Feb 24, 2017

I just changed the oil in my car at a 3,000 mile interval, 5000 miles total. I weighed my oil catch pan before and after the oil change and calculated based on the weight of the oil that I got 8.6 quarts out. I originally put in 10.5 quarts and subsequently added another half quart around 2,500 miles into my 3000 mile interval so the total oil volume in the engine was actually 11 quarts.

My thoughts are I didn't weigh the oil filter so some amont of oil was in that filter but I do not know how much. Additionally there was some residual oil left in the motor, how much I do not know.

So essentially I got 8.6 quarts out and the total volume in the motor was 11 quarts. What do you guys think about that? Am I losing oil or is that pretty close to an expected volume out with residual volume left in the filter and engine, which would be estimated at 2.4 quarts unaccounted for.

Thanks.

firestarter2 · Feb 24, 2017

My gut says you lost enough from the filter that its probably not a big deal.

barstowpo · Feb 24, 2017

That's an interesting question. I usually let mine drain over night when changing my oil. I never have much mess from the filter. I have never paid much attention to hom much I drain. I will look more carefully next time.

Voodooo · Feb 24, 2017

You'll never get it all out without tearing the engine down.
Let's say for example you pour in 10 quarts into the engine with the drain plug removed. And you have a drain pan to catch it as it drains. You're not going to get the 10 quarts back. Maybe 9.5 or so because some of it will sit inside the head and oil pan.

Now let's say you put the drain plug in and filled it with 10 quarts, with a new filter on and started it. Now you drain it into a empty container. Your still not going to get 10 quarts because it's filled all the oil passages, filter, lifters, etc. my guess would be maybe 8.5-8.75 quarts would come out and 1/4 - 3/8 quart from the filter.

It's like digging a hole in dirt. You always have left over because it's not compacted.

I always drain the oil hot at operating temps, pour some new oil into the engine with the drain plug removed and allow the new oil to help flush what old oil is still setting on the oil pan floor. Once I see clean oil draining I install the plug and fill her up. I also add oil to the filter on vehicles that allow.

J_Maher_AMG · Feb 24, 2017

Voodooo said:
You'll never get it all out without tearing the engine down.
Let's say for example you pour in 10 quarts into the engine with the drain plug removed. And you have a drain pan to catch it as it drains. You're not going to get the 10 quarts back. Maybe 9.5 or so because some of it will sit inside the head and oil pan.

Now let's say you put the drain plug in and filled it with 10 quarts, with a new filter on and started it. Now you drain it into a empty container. Your still not going to get 10 quarts because it's filled all the oil passages, filter, lifters, etc. my guess would be maybe 8.5-8.75 quarts would come out and 1/4 - 3/8 quart from the filter.

It's like digging a hole in dirt. You always have left over because it's not compacted.

I always drain the oil hot at operating temps, pour some new oil into the engine with the drain plug removed and allow the new oil to help flush what old oil is still setting on the oil pan floor. Once I see clean oil draining I install the plug and fill her up. I also add oil to the filter on vehicles that allow.

Great tip about pouring some new oil in at the end to flush out the last of the old, like that methodology and will certainly utilize this trick in the future :thumbsup:

Question for you though regarding draining the oil hot Scott, I've always drained mine at slightly warm temperatures, but never at full operating temperatures. I know that the oil absorbs a lot of the heat generated by the engine, but is there any cause for concern with draining the oil when the engine is at full operating temperature? I am thinking that once the oil drains, even though steel/aluminum does not retain heat well, that the internals would still be significantly hot after the oil was drained. Having no medium to transfer the heat to could potentially weaken the steel the over time, especially considering it takes a good while for the oil to completely drain? Have you considered this or do you think it would be a reason not to perform the oil change in this manner?

rancherogt · Feb 24, 2017

J_Maher_AMG said:
Great tip about pouring some new oil in at the end to flush out the last of the old, like that methodology and will certainly utilize this trick in the future

Question for you though regarding draining the oil hot Scott, I've always drained mine at slightly warm temperatures, but never at full operating temperatures. I know that the oil absorbs a lot of the heat generated by the engine, but is there any cause for concern with draining the oil when the engine is at full operating temperature? I am thinking that once the oil drains, even though steel/aluminum does not retain heat well, that the internals would still be significantly hot after the oil was drained. Having no medium to transfer the heat to could potentially weaken the steel the over time, especially considering it takes a good while for the oil to completely drain? Have you considered this or do you think it would be a reason not to perform the oil change in this manner?

Between the residuals oil left in the top of the cylinder heads and what is in the oil cooler and lines would be approximately 1/2 quart or so.

As for hot or warm just makes how fast the oil drains out of the engine. With modern detergent oils which hold contaminants in suspension you could drain cold but that take way way more time. I don't have all day so I drain hot.

When I do oil changes buy the time I get back from my drive to heat the oil and get all things in place around 10-15 minutes most or all of the metals in the engine have equalized in there heat and have little to no bearing on the changing of the oil.

Strokerswild · Feb 24, 2017

Voodooo said:
You'll never get it all out without tearing the engine down.
Let's say for example you pour in 10 quarts into the engine with the drain plug removed. And you have a drain pan to catch it as it drains. You're not going to get the 10 quarts back. Maybe 9.5 or so because some of it will sit inside the head and oil pan.

Now let's say you put the drain plug in and filled it with 10 quarts, with a new filter on and started it. Now you drain it into a empty container. Your still not going to get 10 quarts because it's filled all the oil passages, filter, lifters, etc. my guess would be maybe 8.5-8.75 quarts would come out and 1/4 - 3/8 quart from the filter.

It's like digging a hole in dirt. You always have left over because it's not compacted.

I always drain the oil hot at operating temps, pour some new oil into the engine with the drain plug removed and allow the new oil to help flush what old oil is still setting on the oil pan floor. Once I see clean oil draining I install the plug and fill her up. I also add oil to the filter on vehicles that allow.

This.

I have always changed oil hot. As in pull in the car after a thrash and crack the drain plug hot. Oil is thinner and will carry out any super fine crud in the pan.

vudupwr · Feb 24, 2017

Great tip about adding fresh oil to flush out the used oil. I always change oil in all my machines when they're hot. Been lurking for quite some time gathering knowledge. Thought I'd give credit where credit is due. Thanks!

GT_Dave · Feb 24, 2017

You are all goofy if you spend more than 5 minutes draining your oil pan. To answer the OP's question I just did a fluid capacity test on my oil cooler radiator I am waiting to install. The cooler alone holds 15 ounces of oil, the hoses would hold about the same. That means you have at least a quart of old oil left in the system that you won't get out unless you remove hoses and force that oil out of the cooling system. Why would anyone spend the time to get those last few drops of oil out of the pan, or pour fresh oil in to flush the pan when you have a quart of old oil waiting to undo all the effort as soon as you start the engine?

Voodooo · Feb 24, 2017

J_Maher_AMG said:
Great tip about pouring some new oil in at the end to flush out the last of the old, like that methodology and will certainly utilize this trick in the future

Question for you though regarding draining the oil hot Scott, I've always drained mine at slightly warm temperatures, but never at full operating temperatures. I know that the oil absorbs a lot of the heat generated by the engine, but is there any cause for concern with draining the oil when the engine is at full operating temperature? I am thinking that once the oil drains, even though steel/aluminum does not retain heat well, that the internals would still be significantly hot after the oil was drained. Having no medium to transfer the heat to could potentially weaken the steel the over time, especially considering it takes a good while for the oil to completely drain? Have you considered this or do you think it would be a reason not to perform the oil change in this manner?

We're talking 180-220 degrees Fahrenheit. If we were talking about bringing steel and aluminum to their red or near red hot state and air, water or oil hardening them then that would be a concern.
Draining the oil hot helps remove any "gunk" and impurities suspended in the oil as it drains. By the time you drain the oil, remove the filter and refill the crankcase with new oil the engine has already cooled quite a bit. If you were talking about dumping liquid nitrogen into the engine that would be bad on a hot engine lol.

I also use filter magnets on my filters. It's cheap easy insurance and never wears out. Just my 2 cents

machsmith · Feb 24, 2017

Voodooo said:
We're talking 180-220 degrees Fahrenheit. If we were talking about bringing steel and aluminum to their red or near red hot state and air, water or oil hardening them then that would be a concern.
Draining the oil hot helps remove any "gunk" and impurities suspended in the oil as it drains. By the time you drain the oil, remove the filter and refill the crankcase with new oil the engine has already cooled quite a bit. If you were talking about dumping liquid nitrogen into the engine that would be bad on a hot engine lol.

I also use filter magnets on my filters. It's cheap easy insurance and never wears out. Just my 2 cents

What filter magnets do you recommend Scott? Was thinking about strapping a magnet to the bottom of the oil pan and removing at each oil change. Was thinking of using velcro "Pouch" and a nice size magnet hugging the bottom of the pan. Undo and change. As long as a person uses rubbing alcohol to clean the points where the sticky will go, it will hold it like a rock.

Edit:, maybe I'll tear apart and old large pioneer speaker haha.. nahh...that would probably has so much pull it would shatter the OPG

MCarsFan · Feb 24, 2017

What about lifting the front a bit more so it drains at an angle?

Voodooo · Feb 24, 2017

machsmith said:
What filter magnets do you recommend Scott? Was thinking about strapping a magnet to the bottom of the oil pan and removing at each oil change. Was thinking of using velcro "Pouch" and a nice size magnet hugging the bottom of the pan. Undo and change. As long as a person uses rubbing alcohol to clean the points where the sticky will go, it will hold it like a rock.

Edit:, maybe I'll tear apart and old large pioneer speaker haha.. nahh...that would probably has so much pull it would shatter the OPG

Putting a magnet on the composite pan won't do any good. That will just collect it to where the magnet is. You want it on the filter so when it's trapped inside the filter it gets thrown away when changed.
I've been using Filter-Mags for years.
I actually used to use a speaker magnet years ago when I was a young buck.

Lmao at shatter the OPG

http://www.filtermag.com/

machsmith · Feb 24, 2017

Voodooo said:
Putting a magnet on the composite pan won't do any good. That will just collect it to where the magnet is. You want it on the filter so when it's trapped inside the filter it gets thrown away when changed.
I've been using Filter-Mags for years.
I actually used to use a speaker magnet years ago when I was a young buck.

Lmao at shatter the OPG

http://www.filtermag.com/

Thanks man. My idea was to remove the magnet right before I pull the plug so the contaminant flow out of bottom of the pan.
Yeah, the filter is a lot better idea, I hate the thought of anything on the filter but I'll do it anyway.

Voodooo · Feb 24, 2017

machsmith said:
Thanks man. My idea was to remove the magnet right before I pull the plug so the contaminant flow out of bottom of the pan.
Yeah, the filter is a lot better idea, I hate the thought of anything on the filter but I'll do it anyway.

What do you mean? That magnet isn't gonna fall off the filter. It's rare earth magnets and is a strong pull. Hell it may help keep the filter from falling off.

How much old oil is left in an engine after an oil change?

EF300

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firestarter2

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barstowpo

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Voodooo

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J_Maher_AMG

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rancherogt

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