After you drain, how much is still in your engine?

[ekpolk]

 Originally Posted By: _phil_

There's surely not too much wrong with the old oil. It was being used to lubricate the engine 5 minutes before you drained it! I bet if someone mixed 10% or so drained oil with the new oil and had a VOA done it would look pretty much the same as the VOA on an uncontaminated oil.

Maybe, maybe not. I would think that the answer to that question depends largely upon three variables. First, what is the total oil volume; second, what is the retained oil volume; and third, what is the condition of the retained old oil. Absent a specific analysis of these three factors, such generalizations are fairly meaningless. Can we agree that there'd be a difference between the outcomes of one car that has a total capacity of six quarts, retains two old quarts, and had not had a change in 20k miles; and a car that has a total capacity of six quarts, retains 0.5 qts, and had a change 3k miles ago?????

 

[Nickdfresh]

 Originally Posted By: mozart

 Originally Posted By: Mark888

Probably about half a quart. Most vehicles will give a spec for the amount of oil that is put in at the factory and how much is needed for an oil change, and the difference is obviously how much stays in after an oil drain (because of some at the bottom of the sump or just clinging to engine parts). But some of it stays in the filter that gets changed, so actual amount may be less.

I know I'm gonna get flamed for this, but I would think flushing with some fresh oil would help wash the remaining dirty oil out and exchanging it with clean. I'm talking about just pouring fresh oil in while the drain plug is removed. Maybe a 1/2 quart. Last time I asked about this I was called all kinds of crazy.

It's not crazy and it does work on a car that has seen some abuse as far as OCIs go. I wouldn't waste the oil if the car has been well maintained though...

 

[c3po]

On my Marauder I take the oil cap off and pull the dipstick before draining the oil, it seems to come out faster. I do the same thing on my El Camino, but since my oil fill hole on my Edelbrock valve covers is through the breather hole, I take out my PCV Valve and the breather. I know that I am not getting all of the oil out of the engine but I feel better since the oil drains faster.

 

[BuickGN]

I had a preluber on the GN. After the oil was finished draining from the pan I would fire up the preluber to empty all the galleys and such. I would get 1/2 quart extra before the addition of the oil cooler. After the cooler it was over a quart. So the answer is on my particular car, just under half a quart is left in the passage ways. This was also with the old oil filter on. So if the ADBV was working well, very, very little oil is still left in the engine galleys after draining the pan and replacing the filter.

 

[_phil_]

 Originally Posted By: ekpolk

 Originally Posted By: _phil_

There's surely not too much wrong with the old oil. It was being used to lubricate the engine 5 minutes before you drained it! I bet if someone mixed 10% or so drained oil with the new oil and had a VOA done it would look pretty much the same as the VOA on an uncontaminated oil.

Maybe, maybe not. I would think that the answer to that question depends largely upon three variables. First, what is the total oil volume; second, what is the retained oil volume; and third, what is the condition of the retained old oil. Absent a specific analysis of these three factors, such generalizations are fairly meaningless. Can we agree that there'd be a difference between the outcomes of one car that has a total capacity of six quarts, retains two old quarts, and had not had a change in 20k miles; and a car that has a total capacity of six quarts, retains 0.5 qts, and had a change 3k miles ago?????

Agreed! But 33% is not 10% as I generalized. ;-) My point was that a preoccupation with absolute cleanliness and the last "cupful" of oil is just a feel-good exercise. We all have some of those but it ought be seen for what it is.