Which rear diff fluid do I need for Dana 70HD?

1989 R3500 · Aug 6, 2020

I'm getting ready to buy my parts for the rear differential on my 89 Chevy R3500 dually.
Can someone tell me which diff oil is best? I.e 75/90, 75/140 etc.

I'm probably going with Royal purple or Lucas.

Thanks in advance.

AuroraGirl · Aug 6, 2020

Is that a 14 bolt or is it something else? Most manuals say 80w90 unless in Canada (or just coldser climates) but I guess do you have any modifications like locker or posi? Depending on that miht need additives.

AuroraGirl · Aug 7, 2020

nvm i didnt see your title said dana70hd. do you have an owners manual for that year? if so, it should list a fluid viscosity to use, but the spec it suggests will likely be superseded. gl-5 is what mine asks for

this is from 1989 truck manual. 80w-90 GL-5

ali_c20 · Aug 7, 2020

The important thing is that it's GL5 for high pressures in the hypoid gear setup of the differential. 75w-140 if you use your truck for towing and long distances, but it's double the $ as 80w-90.

AuroraGirl · Aug 7, 2020

gl-4 has the compatibility with bronze/copper in old gearboxes

Paladin · Aug 7, 2020

I have exact same differential. Been using Castrol Hypoy-C 80w90, no problems!! :cheers:

1989 R3500 · Aug 7, 2020

Thanks for the replies. I ordered Amsoils' 80w90 synthetic this afternoon.

AuroraGirl · Aug 8, 2020

1989 R3500 said:
Thanks for the replies. I ordered Amsoils' 80w90 synthetic this afternoon.

thats a lot of fluid, but its a lot of good fluid! Make sure you got a good new breather and tube

and if yoiu are going big or go home, id put a cover with a drain and fill plug

Which rear diff fluid do I need for Dana 70HD?

1989 R3500

Junior Member

AuroraGirl

Full Access Member

AuroraGirl

Full Access Member

ali_c20

Full Access Member

AuroraGirl

Full Access Member

Paladin

"Teufelshunde"

1989 R3500

Junior Member

AuroraGirl

Full Access Member

Similar threads

Latest posts

Forum statistics