Saving wear and tear on an engine while waiting for the oil filter to fill up.

Dear Car Talk

Dear Car Talk | Oct 01, 1996

Dear Tom and Ray:

I change the oil on our 1988 and 1991 Ford Tempos. When I start the engine
right after an oil change, the oil light stays on for two or three seconds
until the oil filter fills up. The filter is almost horizontal on the
engine when installed, and will hold very little oil. So I can't fill it up
ahead of time. Any suggestions on how to minimize those two or three
seconds of extra wear and tear before the oil pumps through the system? I
cringe until that oil light goes off. -- John

RAY: I always see my brother cringe when he starts his car, too, John. But
I'm not sure if he's cringing because he's afraid it won't start or because
he's afraid it will!

TOM: Actually, you're right to worry a little bit, John. Some damage IS
done during those few seconds without oil pressure. That's why on cars
where the oil filter hangs down, we do recommend filling the filter with
oil before installing it. That way, full pressure is reached almost right

RAY: In cases where that's not possible, I'd suggest two things. First,
whatever you do, don't rev the engine as soon as you start it. That would
certainly hasten the demise of these two world-class automobiles.

TOM: And if you really want to be good to these cars, you can disconnect
the coil wire or the wiring harness that goes to the electronic ignition.
Without those, the car will crank, but it won't start. And while it's
cranking, the oil pump will do its job. So you'll be filling up the filter
and building up oil pressure while the engine is turning very slowly -- at,
say, 100 rpm, vs. 1,000-2,000 rpm once it actually starts.

RAY: And even my brother knows enough math to understand that running the
engine on low oil pressure at 100 rpm for two seconds does less damage than
running it at 1,000 rpm for two seconds.

TOM: After you've cranked it for a few seconds, you can hook the ignition
back in, and start it up. And you shouldn't see the oil light at all. The
only cringing will be from the realization that you've just added to the
number of miles you'll have to spend driving that Tempo!

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