What is the correct gear oil to use?

1958fwdlk Posted 2021-12-20 7:02 AM (#617786) Subject: What is the correct gear oil to use? Member Posts: 6 In the 1958 Fury, what is the correct gear oil to use for the differential? Experience (my mind is slipping a little) but 75-80 or 80-90 should be used correct? Thank you for any help you can provide. Happy Holidays to all finsruskw Posted 2021-12-20 8:24 AM (#617787 - in reply to #617786) Subject: Re: What is the correct gear oil to use? Expert Posts: 2289 Location: Eastern Iowa Whatever the FSM dictates! I've always used 80-90, the stinky stuff! finsruskw Posted 2021-12-20 8:24 AM (#617788 - in reply to #617786) Subject: Re: What is the correct gear oil to use? Expert Posts: 2289 Location: Eastern Iowa Whatever the FSM dictates! I've always used 80-90, the stinky stuff! 1958fwdlk Posted 2021-12-20 8:58 AM (#617789 - in reply to #617786) Subject: RE: What is the correct gear oil to use? Member Posts: 6 Thank you! 57chizler Posted 2021-12-20 12:09 PM (#617792 - in reply to #617786) Subject: RE: What is the correct gear oil to use? Expert Posts: 3778 Location: NorCal Depends on whether or not you have Sure-Grip, LS differentials require GL-5 oils while GL-4 will work for non-LS. Personally, I use only GL-5 in everything (Synthetic 75W-90). The viscosity recommendations have changed over the years but the components haven't changed.