Rear Axle/Differential Gear Oil

[JDPisano]

Good Evening!

I need some assistance from the wizards on this forum with regards to the proper type of Rear Axle/Differential Gear Oil.

The manuals for my car list the oil type/specification as Hypoid gear oil, viscosity SAE 90EP (Duckhams Hypoid 90S). My problem is I cannot find SAE 90EP anywhere. It seems nobody carries straight 90 weight.

Can anyone tell me where I can find this oil type/specification or what is the equivalent type being sold today?

Thank you,
John

 

[bthompson]

I use Castrol Hypoy-C 80W-90. Works fine, and available everywhere. I remember hearing Castrol specifically works for older cars with bronzy bits, but don't have the details on hand.

 

[jlaird]

Any good brand 90 wt will work fine.

 

[Guest]

what they said...

 

[JDPisano]

Thank you all for the reponses. It seems none of my local stores carry Castrol Hypoy-C 80W-90. I did find Valvoline durablen Synthetic gear oil at 80W90. Specs are listed below. Does anyone have any thought on this brand/type? I read somewhere that GL-5 types containing sulfur can damage our older internal parts. Is this accurate information? I noticed the Castrol Hypoy-C 80W-90 also lists GL-5 in the specifications.

Thanks,
John


Part Number: 280
Weight: 2.1 lbs
Weight: Oil Viscosity 80W-90

Flash Point (Deg): 430
Oil Composition: Semi-Synthetic
Oil Type: Gearbox
Pour Point (Deg): -32.8
SAE Oil Weight: 80W90
Standards: API Services GL-5, GL-4, MT-1
Type: Plastic quart bottle

 

[JPSmit]

From memory, there have been mixed results with synthetic - some say it attacks the bronze, others have no issues. I just went with plain old 90W gear oil - works fine.

 

[RickB]

It eats up the yellow metal.
Synthetic doesn't and neither does GL-4.
Synthetic can be a problem if your seals are old, so be careful.

 

[RickB]

JP, really? I haven't heard that before about synthetic.

 

[JPSmit]

JP, really? I haven't heard that before about synthetic.

Like I said Rick - vague recollection.

 

[RickB]

Maybe it was just the negative about the old seals leaking with synthetic then.

 

[JPSmit]

Maybe it was just the negative about the old seals leaking with synthetic then.

OK, found one of the threads - and it was you who said it But it was transmissions and synchros - not rear ends

https://tinyurl.com/2uzhqso

 

[KSIS]

Have you tried Tractor Supply. The have the "odd" oils for older farm equipment. Thats where i got mine.

 

[JDPisano]

Thank you all again. I did call several local Tractor supply stores. Unfortunately, none of them had straight 90W. However, after calling all over the local area I did manage to find the Castrol Hypoy-C 80W-90 and bought a few bottles to keep in the inventory.

 

[jlaird]

Grats, now you have a life time supply.