Currently... 1)Fram/Champion -and- 2)Wix/Purolator/Mann+Hummel are the only two major oil-filter manufacturers in the USA. Making aftermarket, OEM, and third-party-branded oil filters. Also, given that there are only two consolidated manufacturers, quality of the USA oil filters seem to have...
I always do maintenance myself. I don't trust others touching my vehicles, and their prices. Oil changes, rear diff fluid, PTU fluid, transmission fluid, tire rotations.... all done by me.
Understood... If the additive was required, it would be listed in the materials needed. I was just commenting on what BillBillW had replied to me about-
"No. It must have the special additives (friction modifiers) for the clutch packs. Regular gear oil is only good for non-limited slip...
Mobil 1 gear oils have a Limited Slip additive... The LS on the bottle.
Mobil 1 Synthetic Gear Lube LS 75W-90 contains special friction modifiers designed for limited slip-type differentials. In most applications, the addition of special LS (limited slip) additives is not required.
Been changing my oil every 3,000 with Castrol synthetic blend. Will switch to full synthetic after I do my first intake cleaning with seafoam spray. I will be using my oil life monitor as a reminder to clean the intake with some seafoam spray.