Modern oils are all basically the same until you get 4K or over on the oil. The better grades don't loose their additives and viscosity as soon. Oil will all return to 30W after many miles as that is the natural refined grade of all oil.
Synthetic oils last longer (about 30%) but they still have to be changed. With a good frequesncy of oil change it is thew consumers chaoice.
Rotilla T is a good oil but it has extra detergents for diesel applications. It doesn't work well on older engines unless it is the only oil the vehicle has used.
The MOST important consideration is viscosity. Use what the manufacturer states. It's OK in very hot applicatons (100+) to go from 5w-30 to 10W-30 and that applies only to older engine with 70K+.
The big NO-NO is to use 10W-40 unless the vehicle calls for it. It will void warranties in many cases especially Ford when the require 5W-20 and soon to 0W-20.
The bottom line is use what you want, I only gave my opinion based on 40+ years of garage ownership and fleet management.
Tuesday, May 9th, 2006 AT 11:36 AM