Gear Oil
10-09-2016, 03:51 AM
#3
LS1Tech Administrator
iTrader: (3)
Join Date: Nov 2001
Location: Schiller Park, IL Member: #317
Posts: 32,362
Likes: 0
Received 1,794 Likes
on
1,278 Posts
That looks like a newer bottle design, wonder if it replaced the recommended synthetic for the '99+ cars?
Personally I wouldn't use it because, even though it doesn't specify synthetic on the label, the 75w90 was traditionally a synthetic gear lube which is not recommended for usage in the '98 Auburn diff. Some individuals have reported no issues using GM synthetic in the Auburn, but issues only with other brands of synthetic.
Regardless, the factory recommendation for the stock '98 Auburn rear was 80w90 conventional with one 4oz. bottle of LSD additive. If you still have the stock diff in your '98, that's what I would stick with.
The original part number for proper '98 service lube was #12345977. This was then replaced by #89021669. Both were 80w90 conventional, API GL-5. I still have a ton of old bottles so I haven't needed to order any in years. I don't know if that last part number is still active or if it's been replaced. The corrected LSD additive, last time I order it, was #1052358.
Personally I wouldn't use it because, even though it doesn't specify synthetic on the label, the 75w90 was traditionally a synthetic gear lube which is not recommended for usage in the '98 Auburn diff. Some individuals have reported no issues using GM synthetic in the Auburn, but issues only with other brands of synthetic.
Regardless, the factory recommendation for the stock '98 Auburn rear was 80w90 conventional with one 4oz. bottle of LSD additive. If you still have the stock diff in your '98, that's what I would stick with.
The original part number for proper '98 service lube was #12345977. This was then replaced by #89021669. Both were 80w90 conventional, API GL-5. I still have a ton of old bottles so I haven't needed to order any in years. I don't know if that last part number is still active or if it's been replaced. The corrected LSD additive, last time I order it, was #1052358.
10-09-2016, 10:16 AM
#5
That looks like a newer bottle design, wonder if it replaced the recommended synthetic for the '99+ cars?
Personally I wouldn't use it because, even though it doesn't specify synthetic on the label, the 75w90 was traditionally a synthetic gear lube which is not recommended for usage in the '98 Auburn diff. Some individuals have reported no issues using GM synthetic in the Auburn, but issues only with other brands of synthetic.
Regardless, the factory recommendation for the stock '98 Auburn rear was 80w90 conventional with one 4oz. bottle of LSD additive. If you still have the stock diff in your '98, that's what I would stick with.
The original part number for proper '98 service lube was #12345977. This was then replaced by #89021669. Both were 80w90 conventional, API GL-5. I still have a ton of old bottles so I haven't needed to order any in years. I don't know if that last part number is still active or if it's been replaced. The corrected LSD additive, last time I order it, was #1052358.
Personally I wouldn't use it because, even though it doesn't specify synthetic on the label, the 75w90 was traditionally a synthetic gear lube which is not recommended for usage in the '98 Auburn diff. Some individuals have reported no issues using GM synthetic in the Auburn, but issues only with other brands of synthetic.
Regardless, the factory recommendation for the stock '98 Auburn rear was 80w90 conventional with one 4oz. bottle of LSD additive. If you still have the stock diff in your '98, that's what I would stick with.
The original part number for proper '98 service lube was #12345977. This was then replaced by #89021669. Both were 80w90 conventional, API GL-5. I still have a ton of old bottles so I haven't needed to order any in years. I don't know if that last part number is still active or if it's been replaced. The corrected LSD additive, last time I order it, was #1052358.
I think I will try and find some of what you suggested just to be safe. I'm getting a little noise from the rear and appear to have a small leak. I will replace the gasket and the oil, Thanx again.
