Was just having this conversation with a client who runs an autoshop the
other day. He says that all modern engines that say 5W-something on them
need a 5W-something oil. (I was fixing his alarm and phone systems).


While I have only been paid as a machinist for 15 years, They have been
paying me to be a mechanic since 75 in various jobs from shipyards to
Ferrari dealerships.
Use the grades the factory says in your truck.
Don't use an SM rated oil, (low zinc content) in a vehicle without a
catalytic converter. It protects the cat, but doesn't protect camshafts.
Don't use C rated (diesel) oils in a gas engine that has a cat, it will ruin
it..
Don't use an "energy conserving" oil in a vehicle that has a wet clutch.
I use Delo or Rotella in all of my fleet, but in grades appropriate to the
engine makers specs, season, and mileage.
--
Stupendous Man,
Defender of Freedom, Advocate of Liberty