I got my rebuilt rear back from Monzaz - so far so good! It has a Eaton clutch type posi in it. p What brand 80/90 weight oil do you guys like for this application? I plan to use the GM posi additive btw. - Bill
Bill, in a situation like this, I'd only follow Monzaz's recommendation for lube, additive if any, break in procedure if any, especially if he's standing behind his work. Devon
Eaton wants you to use regular dino oil. Synthetic will void the warranty. I used Valvoline 80W/90 and one container of GM Posi additive. I ran the car easy for 200 miles, then drained and refilled with the same fluid. Honestly, I think any major brand Gear Oil is fine.
Any Mineral based oil will do the job 80-90, 85-140 etc...No need for any SPECIAL fluid. Just be sure the fluid is at the correct level after a few runs as the posi unit will hold some fluid up in the units clutches and the dry diff case axle tubes also which will lower the fluid level from the fill plug (which is also the fill level also). SO double check that fluid LEVEL - it is the rears life line. GM is fine, Valvoline is fine (just no synthetic) Additive 4-8 oz as needed to stop clutch chatter. no more than 5-10 min runs on the first 2-3 runs and make certain you get a FULL cool down of the rear as this is what will Rockwell the ring and pinion gears to the full potential hardness need to last a good long life. No long freeway drive for at least some 200 miles would be nice and better for the gears. Take care, be safe and have fun. Jim
