Using USED oil as a top off?

Status
Not open for further replies.
Joined
Jun 25, 2014
Messages
3,423
Location
IL
Since we all pretty much change oil before the oil's E.O.L., if oil needs added after O.C.(leaks, burning, etc.), then why not save some used filtered oil from previous O.C. to top off?
 
Last edited:
It's possible. It would work.
So would old fryer oil. Or even new vegetable oil. Or bacon grease.
 
Then stop changing your oil before its e.o.l.

If you decided to change it, then you must have thought it was no longer good. Then why would you now want to put it back in the engine?

I suppose you could, but how much money are you really saving by doing this? Are finances that tight?
 
I have a BMW buddy who runs Mobil 1 for a yr in his week ender. Putting maybe 1500 miles on it. He uses it in his 575K mile. commuter.
 
Originally Posted By: KingCake
Just run a longer OCI ya dingus.


Without records of UOA's you don't know when that is... and your not saving anything on UOA's(unless you get them for free) just to save money on oil cost.
 
Last edited:
I used to have a civic with nearly 300k miles on it. It used a quart of oil every 1,000 miles so I changed the oil in my other vehicles sooner and put their oil in it. That civic was pretty worn out at that point and eventually one of the cylinders did stop working.
 
Originally Posted By: Vern_in_IL


Without records of UOA's you don't know when that is..

Yet you do know that the oil is still good enough to dump it back into the engine?

Make up your mind.
 
I would just buy a cheap (and fresh) jug of generic brand mineral oil and top up with that. I use to buy Woolworths / Kmart brand 20W-50 to top up an old oil burner of mine. At least I knew that I as was adding to (not subtracting from) the TBN in the sump.
 
I use my catch can for all sorts of fluids so I don't want oil mixed with ATF & PSF being poured back into my engine. I always have .5 qts left over during oil changes and that's usually enough for my top offs anyway.
 
I always have a left over partial quart for top off in the garage.

You could top off with used but it's not worth the effort or the risk of pouring some grimy contaminated oil into your car.

Pony up for a spare quart and don't look back.
 
Originally Posted By: Vern_in_IL
Originally Posted By: KingCake
Just run a longer OCI ya dingus.


Without records of UOA's you don't know when that is... and your not saving anything on UOA's(unless you get them for free) just to save money on oil cost.


You only need to do a UOA once to establish OCI. Maintaining records is free.
 
Originally Posted By: 901Memphis
If an engine is using 1 quart every 1k you don't need to change the oil, just the filter when it's time to remove the built up insolubles.


I've been tempted to do this before with other oil burners. Does sludge build up in the pan eventually and/or is NOACK a bigger concern?
 
Originally Posted By: KingCake
Originally Posted By: 901Memphis
If an engine is using 1 quart every 1k you don't need to change the oil, just the filter when it's time to remove the built up insolubles.


I've been tempted to do this before with other oil burners. Does sludge build up in the pan eventually and/or is NOACK a bigger concern?


I'm sure it varies by applications but in theory 1 quart of oil every 1k is essentially changing the oil just slowly.

You're replenishing the additives and the TBN and the oil filter will continue to trap particles so everything should be fine doing this.

I can see some things sitting on the bottom of the pan if the pickup won't suck them to be filtered but you could always drain the pan every 3 years and see if anything looks off. In this situation it's gonna be a beater and the engine will likely last longer than the rest of the car.
 
Why would you even think of doing this? I still got a small stash of $1 Autozone clearance oil and plenty of $2 synthetic Autozone oil. It's bad enough having to find room to store all of it, I'm not going to keep used oil around.
 
My daughters car is an oil burner, and she never checks it. When she comes down here, it's always low, so I use some of my used motorcycle oil, I change it early, so plenty of life left in it....and I don't have to buy oil just to top up her car.
 
Status
Not open for further replies.
Back
Top