Extended oil drains

[Mattman]

Just a note on the gear oil. I have an emission friendly truck. Everything is intact and working great. I add one gallon of 80/90 gear oil when I change oil. I change every 15,000. Been doing this for six oil changes. Hasn't hurt mine yet to my knowledge. I go the 15,000 and don't have to add any oil between changes.

Going to keep doing it to mine. I have thought 25,000 miles on oil changes would be nice, but oil and filter is cheap. Camshaft and rockers not cheap. Makes me sleep well at night at least.