Gear Oil for 1977 with B8 Rear Axle

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Networker
Bfix "What's a Bronco?"
Bfix "What's a Bronco?"
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Gear Oil for 1977 with B8 Rear Axle

Post by Networker » Tue Aug 23, 2016 5:49 am

I recently bought a 1977 Bronco Sport with 302 / C-4 and Rear Axle Code B8.

My brother is an Amsoil distributor and I would like to change the gear oil to Amsoil. I'm confused on what weight use and whether I should use an additive for the limited slip.

Any help would be appreciated.
Thanks

DirtDonk
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Post by DirtDonk » Wed Aug 31, 2016 11:26 pm

Hey there. Sorry about the delay. Didn't see the post the last time around.

Shouldn't be any confusion really. It's not like the precise weight is so critical, as long as you get it within the normal range. These rigs were built back when single viscosity oils were the norm and multi-vis oils were still almost in the snake-oil world to some.
I would personally use (and do use in fact) a 75w/90 synthetic in the front, rear and transfer case of your Bronco. The manual gear box too, if yours has one.
The transfer case officially takes 50 weight motor oil, but if your synthetic from Amsoil is compatible with "yellow metals" such as the soft bronze stuff, it should flow and protect nicely even where motor oil was recommended. But when in doubt, 50 wt will get you there for the t-case.

Your front Dana 44 and rear Ford 9" would love the 75w/90 in most conditions. I hate changing oil for the season (lucky not much of an issue here in CA) and that weight seems to cover all the bases nicely. In a truck hauling heavy loads in the desert at 120 degrees F, I might go up a notch, but for most of us our Broncos don't fall into that category.

The limited slip should not need additive with the synthetics. I would not put it in unless it's needed after trying it out for a week with just the straight gear lube. But it'll say on the side of the container if it's "compatible" or "for use with" Limited-Slip diffs.

Good luck. Assuming by now you probably already decided on something, but just in case, hope that info helps.

Paul
'71 Bronco - 302 4v
3.5" WH/Skyjacker Lift
33 x 11.50 x15 Thornbirds on 15x7 Enkei's
Kayline soft top
Hanson bumpers
Dual batteries, Large 1G alt.

WWW.WILDHORSES4X4.COM :mrgreen:

Networker
Bfix "What's a Bronco?"
Bfix "What's a Bronco?"
Posts: 2
Joined: Tue Aug 23, 2016 5:36 am

Post by Networker » Sat Sep 03, 2016 6:19 am

Thanks, Paul

I have not bought the oil yet, so this is definitely helpful. I'll go with the Amsoil 75W-90 in all 3 units.

Just put on a set of BFG All-Terrain KO2 10.50x33 15's with Pro Comp Rock Crawler steel wheels. I've only driven about 500 miles on them, but so far these get a top rating. Plus they look very old school with the RWL facing out.

This thing is without a doubt the most fun vehicle I've ever owned.

Thanks again,
Chuck

DirtDonk
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Post by DirtDonk » Wed Sep 07, 2016 3:17 pm

Glad to hear it. Both the oil choice and the fun factor!
Just be patient with all the questions when you pull in to fill up with gas, and the thumbs-up when driving down the road.

Paul
'71 Bronco - 302 4v
3.5" WH/Skyjacker Lift
33 x 11.50 x15 Thornbirds on 15x7 Enkei's
Kayline soft top
Hanson bumpers
Dual batteries, Large 1G alt.

WWW.WILDHORSES4X4.COM :mrgreen:

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