damaged differential advice

[Duke W.]

Re: damaged differential advice

85W-140 is commonly used in heavy duty truck axles. It will probably do no harm in a car axle, but it will increase driveline loss due to being higher viscosity and will probably run hotter.

In any event, particularly for the modest way most of us drive out vintage car, I believe the OE recommended 80W-90 is best all-around choice.

Duke

[Tim D.]

Re: damaged differential advice

Hi Gary,

Thanks for reminding me to heat cycle 10 times and change oil and posi-lube at 500 miles. You are correct, with the drain plug installed, it will be a piece of cake and make me way more inclined to change it again every 30,000 miles.

I'm glad you like the photos of my car. Thanks for the compliments. The new differential/rear axel/rear end?? (I can't seem to remember the correct name) is performing flawlessly thanks to you. I love it!

Tim

[Gary R.]

Re: damaged differential advice

Tim
Great to hear now go get some more miles on it!!!

Duke,
I have run 90 wt without issue, I use it to lube the new bearings during assembly. As far as loss, maybe I really cant' say other then my son runs a 12 bolt IRS I built for his 75 and his first time at the track a couple of weeks ago he ran 11.93 if I recall so I bet it's not much.

The heat concern is something I've check with a IR gun and have a guy in FL who documents everything on his car check his. Same type of build on the 10 bolt,super 10 and 12 bolt and temps were running in the 150-200* F range after 30-60 minute runs on the 2 cars.

So I leave it up the car owner but the Lucas oil is what I really like & use in my vettes. With a tuned posi all you need is one bottle of the additive as well.

[Duke W.]

Re: damaged differential advice

Hi Gary,

The new differential/rear axel/rear end?? (I can't seem to remember the correct name) is performing flawlessly thanks to you. I love it!

Tim

The correct term is axle.

Duke

[Tim D.]

Re: damaged differential advice

Duke,

Thanks.....'axle' it is! I should know that after studying my shop manual and AIM etc. while researching my problem.

Tim

[Harry S.]

Re: damaged differential advice

Tim
Run the car through the heat cycles, change the oil at 500 miles. Add in the Lucas 85-140 gear oil and 1 bottle of GM posi additive. Good idea to change it at 30k or 4 years. Since you now have a drain plug it's a piece of cake.
Enjoy the car, the pictures look sharp!

Gary, I probably missed it in the thread. How much (quantity) of Lucas 85-140?

Thanks

[Gary R.]

Re: damaged differential advice

An empty diff holds 60 oz,including the 4 oz of additive. In the car, with it at ride height just fill it until it weeps out the fill hole.