1999 Ford F150 - Motorcraft Oil filters and whatever 5-30 synthetic blend is on sale (usually Mobil)
2004 Ford Mustang GT - Motorcraft oil filters and Castrol Syntec 5w-20
1994 Jeep Cherokee - Exxon 10w-30 oil and whatever filter is on sale
2003 Lexus RX300 - 5w-30 Mobil synthetic blend and a Lexus oil filter
1999 Audi A4 - 5w-30 synthetic blend and an Audi oil filter.
1970 Olds 442 - Delo 15w-40 diesel oil and Baldwin filters
2002 Kubota diesel tractor - 5w-40 Rotella Synthetic diesel oil and Baldwin filters
Mowers, chipper, leaf vac, power washer all ger 15w-40 Rotella diesel oil
I change the oil in the cars every 3 months, and I do not clock mileage.
The Olds gets changed spring and fall, and it is not driven in the winter.
The yard equipment gets 1 oil change per season