I run Amzoil synthetic 75W 90 in my vehicles and it works really well. I've had it in my '85 pickup for at least 10 years. It's especially nice in the winter when the temp is below 0 F for days as the tranny still shifts like it was a hot summer day, and it doesn't thicken up like mud when cold and bog the truck down until it warms up and thins out. Amzoil is located near where I live, so we may be a little bit partial to them vs. other types, but I'm sure the other types work well too.