Not a question but a tech tip

Ok, I’m fairly new here and fairly new to working on car stuff. I’ll try to make it short. My stepson is a big car guy and has been a great help getting the MX road worthy. On my first road trip I had a rear axle bearing fail, came home on a flatbed. My stepson insisted we not only change the rear end oil but actually remove the chunk and make sure no debris from the bearing was there. So all checked out, all back together. We put synthetic oil and supplemental limited slip additive.

The differential was not happy. Grinding and grumbling at every turn. We read on line some rear ends can’t take synthetic oil so I changed it out for non synthetic. My stepson insisted we still add the additive. Grinding was much less but not gone. It did get less the more I drove but never completely gone.

Couldn’t stand it anymore so yesterday I sucked all that oil out again. It’s not very fun. And put in high quality non synthetic gear oil made for limited slip gears with NO ADDITIVE. My wife and I ventured out on a 150 mile pleasure ride today and by half way the rear end grinding was absolutely gone. Smooth as glass.

So, my tip is if you have a small 9” ford limited slip rear end like I do and it’s not happy, change the oil for non synthetic and if yours is happy DONT USE SYNTHETIC if you go to change the oil.

That's very useful since I'm in the middle of my rear-end rebuild for my old truck. Thanks!

Good deal David. Do it right. Trust me, it’s way harder to do it right AFTER it wasn’t.

My car is so much more fun to drive now that it’s 100%. For the first six months it was one drivability issue after another because the previous owner was lazy.

The car doesn’t seem like the same car now. I wouldn’t sell it now for twice what I paid for it it’s that much fun!

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