Thinking about doing a rear differential change and from what I heard I should use a good 75w90 instead of the 75w85 that Toyota / Lexus wanted me to use. Seems like most if not all 75w90 are synthetic and Mobil1, Castrol, Valvoline are the easiest to find in the store, and M1 / Valvoline are the same price (cheaper than Castrol), I'm debating whether to use M1 or Valvoline.
Seems like based on Amsoil's "test" M1 is thinner new but isn't passing some of the MIL spec that Valvoline passes. I personally prefer a thinner oil because it is closer to the manufacture's original spec, would those extra MIL spec really mean anything if my car isn't requesting it?
How different are gear oil between brands for the same price / visc / etc?
Seems like based on Amsoil's "test" M1 is thinner new but isn't passing some of the MIL spec that Valvoline passes. I personally prefer a thinner oil because it is closer to the manufacture's original spec, would those extra MIL spec really mean anything if my car isn't requesting it?
How different are gear oil between brands for the same price / visc / etc?
Last edited: