Extreme extended drain time: How much oil drips out over a week?
- Thread starter jmaster
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Guess we see things a bit different. But from my thinking allowing the upper engine to drain that long has gotta be bad when you start the engine. Oil takes time to fully pump up to fill all the oil system as opposed to short oil change time. The difference is the oil pump is completely drained of oil after a week.
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Patman
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Long time members of this forum will remember that I used to do that occasionally! Other times, when I was switching brands of oil in one of my cars, and wanted to do a UOA to see how that oil was going to perform, I didn't want that new brand mixing with too much of the old brand, so I would drain the oil for a few minutes, and then put the plug back in and put in 2-3 qts of the new oil. I'd then idle the engine for about 30 seconds and then drain it again. Yes, that was a total waste of oil for sure, but I also wanted that test on the oil to be with almost 100% of that particular brand, vs a normal oil change which really only gives you about 85-90% fresh oil, depending on the engine of course.
Not sure if this adds anything. But when I installed my valvomax oil drain system doodad (which I really like by the way), I accidentally overfilled a little bit with new oil. When I drained a little bit out, the oil that drained was crystal clear and brand new. So there was absolutely no visible old/dirty oil that drained down. Maybe that adds nothing, just thought I would share.
Owen Lucas
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I made YT video about this topic, but addressing a hot vs cold oil drain over a 12 hour period.
Overall, it's not worth draining for so long of course. This was just a test to see what would happen with my 2.4l 2AZ-FE engine ( 4qt sump ).
- Hot oil drain over 12 hr period will yield approximately 100ml extra over the 50ml that you would get out of a regular drain when measured after 30 minutes.
- Cold oil drain over 12 hr period will yield approximately 85ml extra over the 40ml that you would get out of a regular drain when measured after 30 minutes.
Overall, it's not worth draining for so long of course. This was just a test to see what would happen with my 2.4l 2AZ-FE engine ( 4qt sump ).
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Interesting thread.
Now, think the opposite - you take your car to a shoddy place for an oil change and the kid puts the drain plug back in it when there’s still a quart left to go. Then adds four quarts to the five quart engine. Done. Oil looks full (because it is), oil looks clean (because it mostly is). Some might do this by accident, others on purpose. Change your own oil.
I’m kidding.
Now, think the opposite - you take your car to a shoddy place for an oil change and the kid puts the drain plug back in it when there’s still a quart left to go. Then adds four quarts to the five quart engine. Done. Oil looks full (because it is), oil looks clean (because it mostly is). Some might do this by accident, others on purpose. Change your own oil.
I’m kidding.
What about parking at the airport for a week? Or leaving one car at home for 2 week vacation? Even if you drain for a week, it won't be any different than just parking your car where most all the oil falls down into the pan.
Its nothing to stress over. A vehicle that has been stored for years will still have an oil film all over the internals.
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Are you forgetting where you are ? Four pages of stressing ..
I understand what you are saying. Here is my view… The oil filter usually has a check valve that allows a lot of resistance to complete drainage along with the gear oil pump. Bet there is no issue at parking at the airport. However draining the oil for a week with the purpose of complete oil removal means the pump is air bound and all oil passages are drained. Personally would not do it, but open to your thoughts.
If you start an engine from a rebuild one critical thing to do is to prime the oil system, even though the engine has assembly lube.
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When I started helping my father in his shop and when it was still cost effective for the customer to have him do oil changes (circa 1970), he described the oil change procedure to me. Me: 
What got my attention was, "Put the drain plug back in when you get a slow drip and don't mess around filling it back up. There are pumps which can lose prime if the crankcase is left empty for an extended period of time."
I don't know how true this is (his frame of reference started prior to WWII) but it's something that I've practiced ever since.
What got my attention was, "Put the drain plug back in when you get a slow drip and don't mess around filling it back up. There are pumps which can lose prime if the crankcase is left empty for an extended period of time."
I don't know how true this is (his frame of reference started prior to WWII) but it's something that I've practiced ever since.
To prove it’s a waste of time. 3 oz for a week of waiting? goes to show, after a handful of minutes, nothing of value is left to come out.
If you let the oil drain for 5 minutes and then rock the vehicle a few times, you would probably get more oil out than this in just a couple more minutes.
the oil pump probably lost its prime. I wonder how long it took to build the pressure up.
Just think how much you could have gotten in a month!
Or year?
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