We use and recommend MOTUL OIL. If you have dog engagement - Motul 75w-140 Gear Competition OilIf you have a synchro gearbox which has a differential as part of it: Motul FF-LSD Type 2 75w-90 or Motul 75w-140 Gear Competition Oil.If you have a synchro gearbox with no differential as part of it: Motul Gear 300 75w-90 or Motul 75w-140 Gear Competition Oil.If you have a synchro gearbox that specifies an ATF: Motul ATF VI If you are still unsure of the correct grade for your gearset, contact your local dealer - https://www.ppgearbox.com/dealers