I read 4 quarts in the manual, but I could be wrong. With the Oasis diff cover I installed, I needed 6 qts.

 

No need to use any RTV sealant as the gasket are reusable. When I changed mine out it took 3 qt for the front diff and 4 for the read diff. I used Amsoil 75/90 severe gear oil as its good for 50K under sever usage and 100K for normal usage. What every brand of gear oil you use check your diff's every 10K so that you know how well your gear oil is holding up and that its GL-5 rated synthetic gear oil. Oh if the gear oil you want to use is not synthetic don't use it as your diffs require synthetic GL-5 gear oil. Also take the covers off your diff so that you can drain out all of the factory junk oil and also so you can see if your gears are burnt or not and to clean any metal build up in the bottom of the diff.