dodgemahal
Well-Known Member
FSM says 90 weight for temps above -10. I've got 75-90 available in the shop, will that work?
What weight oil should I use in my 67 Coronet's 8 3/4 axle?
- Thread starter dodgemahal
- Start date
Yes, the 75W-90 is fine. The 75W weight gives you just a bit less viscosity when very cold. Plain 90 weight is not common anymore. I just changed mine last week and put in Valvoline full synthetic 75W-90. 1966 Coronet 7.25" differential.
I don't think synthetic gear lube is recommended for these differentials.
Where have you seen any info on that? I don't see how synthetic lube would be a problem.
dodgemahal
Well-Known Member
Thanks Jon.
dodgemahal
Well-Known Member
Can you even find gear lube that's not synthetic anymore?
- Local time
- 2:16 AM
- Joined
- Jan 29, 2018
- Messages
- 19,461
- Reaction score
- 63,759
- Location
- Midland Ontario, Canada
Open or SureGrip? If it's a Suregrip you need a bottle of Stinky **** added in. Do not use synthetic oil in a Suregrip...
dodgemahal
Well-Known Member
Pretty sure it's open but I'll double check it.... thanks!
Correct. Never was.
- Local time
- 11:16 PM
- Joined
- Dec 21, 2017
- Messages
- 11,326
- Reaction score
- 17,632
- Location
- taxifornia,soon 2b Arizona.
This is about the fifth time I've posted this.
Had a good friend who owned a rearend shop, specializing in nine inchers
for racing, but would work on everything. Used Torco Dino oil exclusively. If the customer demanded synthetic, Mitch guaranteed the rearend for six seconds or six feet, whichever came first.
He said the synthetic didn't cling enough, lube the bearings well, or provide enough pressure cushion. I'm sure it was a personal preference, derived from LOTS of experience.
Had a good friend who owned a rearend shop, specializing in nine inchers
for racing, but would work on everything. Used Torco Dino oil exclusively. If the customer demanded synthetic, Mitch guaranteed the rearend for six seconds or six feet, whichever came first.
He said the synthetic didn't cling enough, lube the bearings well, or provide enough pressure cushion. I'm sure it was a personal preference, derived from LOTS of experience.
- Local time
- 11:16 PM
- Joined
- Dec 21, 2017
- Messages
- 11,326
- Reaction score
- 17,632
- Location
- taxifornia,soon 2b Arizona.
For Illinois, I think 75-90 would be fine, but I would avoid synthetic.
Here, in southern cal and Arizona, I run straight 140 in my spool nine, and
8 3/4 locker.
Well, I just drive my car normally around town with no racing or hard driving at all. I'm sure I'm fine with synthetic. Most synthetics these days have the friction modifier already in there. That's what my Valvoline bag said. I'm sure it's a different world for racing.
dodgemahal
Well-Known Member
Valvoline full synthetic 75w-90 states: "Compatible with conventional gear lubricants. Recommended for hypoid diffs (conventional and limited slip) where API GL-5 or GL-4 is specified". Didn't say "sure-grip", lol.
Most recently from a small manufacturer of third members. Customer dropped it off for install, instructions specifically said no synthetic gear oil.
Absolutely
Stinky **** . . . That's a technical term ? ? ? ? LOL LOL LOL
- Local time
- 2:16 AM
- Joined
- Jan 29, 2018
- Messages
- 19,461
- Reaction score
- 63,759
- Location
- Midland Ontario, Canada
I always know it's coming in the mail soon, when it's about three towns over!!!
Yes, I have seen some conflicting information from folks and manufacturers regarding new innards in the differential but is there any info on gear oil changes for the original innards such as my 66 Dodge with open diff? Thanks.
Yes there is info in the service manual written directly about your 66 dodge diff.
80w90.
My service manual says straight SAE 90, not 80W-90. And, of course, there was no synthetic gear oil in 1966 so no useful information from that era on using it or not. I'm sure a dino straight 90 would be fine (I live in the warm climes and do not beat on the car at all) but I don't see why the synthetic 75W-90 wouldn't be at least as good or better.
Similar threads
