Refurbished oil

If the oil filter mounting surface is not wiped prior to mounting the replacement filter, 2 things can happen - if the gasket from the oil filter is stuck there and a new filter and gasket is mounted on top of the old filter, you may have a massive oil leak, and any oil residue and dirt on the mating surface can damage the new oil filter gasket or keep it from sealing correctly, resulting in a leak. I've seen engines ruined from double-gasketed oil filters.

The oil light illuminates when there is low oil pressure, IIRC, in the neighborhood of below 8 PSI. At higher engine RPM, more than 8 PSI is needed to lubricate the engine. For example, if enough oil leaks out while cruising on the highway and 12 PSI is needed to lubricate the engine but due to low oil levels, the pressure is only at 10 PSI, the engine could incur damage without the oil pressure warning light coming on. The oil pressure warning light is not an indicator of oil level.

I've never had to use one, but I would not be a fan of a self-threading plug because over time, there is a pretty good chance that it will leak. If the drain plug were stripped, the proper repair would be replacement of the oil pan or removing the oil pan, drilling and re-tapping the threads and using a larger diameter plug.

Until now I thought the oil pressure light was an indication that adequate oil was circulating. Live and learn.

Not removing the pan would seem to be asking for contamination with metal cuttings - yet everyone other than you have said it was ok to use a self-tapping replacement plug and of course install it without removing anything. Would any cutting(s) have to pass through the filter and thus avoid disaster? jl

The indicator lights comes on when you turn the ignition on (even before you start the car) in order to make sure the lights are working. When adequate oil pressure is reached, then the oil pressure indicator light goes off (same concept for the other indicator lights).

Better to learn by reading than by first hand experience!

The main reason I would not want to use a self-tapping plug is because the self-tapping properties remain in the plug, so it could eventually cut away the metal that holds it in place and leak. As far as the metal shavings (known as swarf) getting into the pan, I think the danger of damage from that is pretty minimal. As the plug is being tightened, the pitch of the plug would tend to eject swarf toward the bolt head, not push it into the pan. Any swarf that got into the pan would probably be picked up by the magnets in the pan, trapped in the oil pump pickup screen, or trapped in the oil filter. I would worry about the self-tapping bolt leaking more than the danger from swarf getting into the pan. IMO, the self-tapping plug is a stop-gap measure, not a permanent one.

The reason you should remove the pan when drilling and tapping is that the drill bit will tend to push some swarf into the pan because there is already a hole in the pan, and tapping will do the same thing.