dirty oil

Montblack wrote:
Doing our (vehicle) oil changes, I drain the old oil. I use a "flush
filter" that goes on next. I add (less expensive oil) and run the car
for 20 minutes - while I clean up from the first batch.

On my second oil change, the "flush filter" gets drained and returned
to its (labeled) box on the shelf. A fresh filter is used, then I add
my good oil and I'm all set.

I know a few people who like to do a similar thing for old^Wclassic cars
with engines of unknown provenance. If the engine is not showing obvious
signs of distress like low compression, huge oil leaks, lots of end play
on the crankshaft, or poor power (measured by an ANSI standard seat-of-
the-pants test), they do oil changes on short intervals, like 200 or 300
miles, until the oil stops turning black shortly after the oil change.
Once that happens, they go to an interval of somewhere between 1500 to
3000 miles. The oil does get dark by the end of this longer interval.

Many of the engines are old enough to not have oil filters as we know
them, so a "flush filter" isn't used for this process. This is also why
some of the owners prefer a "normal" change interval that is pretty short
by new-car standards. They don't expect this treatment to get them
another 100,000 miles before a rebuild or swap, but they do think it
helps the engine last a little longer than it ordinarily would. This
gives them a bit more time to drive the car and work out the rest of
the problems, and to get the parts together for an engine rebuild.

Matt Roberds