From good sources on this forum, I've learned that our manual transmissions and transfer cases require a GL-4 gear oil due to yellow metals used internally. I've found 2 good options: Amsoil Synthetic Manual Transmission & Transaxle Gear Lube and RED LINE MTL® 75W80 GL-4 GEAR OIL. I also own a Jeep TJ with an AX-15 manual 5 speed transmission that calls for GL-4. Quite a few technicians, even at dealerships, apparently recommend using a synthetic 10W-30 motor oil in the AX-15. Could this be a viable alternative to the GL-4 in our Roxors???