Do You Keep a Spare Oil Filter Housing on Hand for Cartridge Filters?

Good suggestion about marking the cap and housing. l will probably scribe mine before the next oil change. But ****ed if I throw away a new o-ring instead of replacing the old one.

Absolutely! I can't think of a single good reason to not replace the housing/cap o-ring, when the filter comes with it. It takes <30 seconds to remove the old o-ring, lube the new o-ring, and install it in the groove.