Originally Posted By: Vern_in_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?
If oil were really dear, this idea might have some merit for the truly cheap or impecunious.
In a country where you can buy oil meeting any spec for less than $2.50/qt if you pay any attention, why bother with the potential trouble?
It's not as though you'd be saving any real money.
If one has a real leaker/burner, farm oriented chains typically offer their store brand oil on sale, especially in the 15W-40 grade, for well under a buck and a half a quart.
You'd save so little using used oil of unknown quality, and you have no idea what the viscosity, TBN, TAN and additives are that it hardly seems worth bothering with.
Lots of risk for little return.