Happy Holidays to All. I am planning on changing my differential (front and rear) and transfer case fluids to AMS Oil Severe gear. I read the owners manual and it says Toyota recommends 75W90 for the front diff. and the transfer case, but recommends SAE 90 for the rear diff. Can I just use severe gear 75w90 in all 3? Has anyone done this? What would be the benefits and/ or draw backs?