• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

Rear Axle/Differential Gear Oil

Share this page

J

JDPisano

Freshman Member
Offline
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
 
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.
 
Any good brand 90 wt will work fine.
 
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
 
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.
 
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.
 
JP, really? I haven't heard that before about synthetic.
 
RickB said:
JP, really? I haven't heard that before about synthetic.
Click to expand...

Like I said Rick - vague recollection. :crazyeyes:
 
Maybe it was just the negative about the old seals leaking with synthetic then.
 
RickB said:
Maybe it was just the negative about the old seals leaking with synthetic then.
Click to expand...

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

https://tinyurl.com/2uzhqso
 
Have you tried Tractor Supply. The have the "odd" oils for older farm equipment. Thats where i got mine.
 
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. :smile:
 
Grats, now you have a life time supply.
 
Back
Top