Mobil 1 oil

[tchb]

Just changed the truck oil at 3500 miles and next the RV.

[76Bonneville]

2001 Ford with a 7.3 450,000 miles 15qts change oil every 10,000 and a filter in between at 5000.
Circle boat with a 509 14qts once a season unless there's something that doesn't look right.
Family jet boat 10qts once a year

All running synthetic oil