So my rear diff cover has rusted so bad it has begun to leak leaving a small plate sized stain each night. Slow drip but annoying. Anyway, until I get around to changing the cover I want to add oil through the fill hole to top it off. I did the pinky finger test and had all of the first knuckle in before I felt fluid, so I know it needs it.

Question: I have the G80 rear end. Could I just use 75-90 Synthetic instead of using a straight 75-90 and have to also put the additive in?

Or, could I just top it off with straight 75-90 without the additive.

What do you guys recommend and is there a trick to adding the fluid that works well. Seems like I used a turkey baster the last time I did it.

Thanks!

 

well... the BEST thing to do is to fix the leak. but until you get around to it youre trying to keep lubrication in it, so you can keep adding fluid if you want too, but seems like it'd be cheaper to just get a cover and gasket and fix it being the price of 75w90 synthetic is so high and who knows how much additive you are losing.

anyway if you want to keep up with the false economy and keep dumping expensive lube on the ground, I'd suggest instead add 80/90 gl-5 or even if you can find regular 90 weight oil... its probably cheaper and you'll be ok to drive it as long as you don't go into an axle slip situation, like off roading or getting stuck.

 

as far as adiing lube, BEST way to do it is to get a suction gun, a turkey baster works well, or get a piece of hose that fits over the spout on the lube bottle, cut the tip off the spout, and squeeze.

 

g80 diff needs no additive.

 

Anybody ever heard of using Zinc plate and adding it to ur rear end oil? I have an unlce that uses it and a little trans fluid mixed in and he has should me fuel mileage improvement. Strange just waned to know if anybody else heard of such a thing?

 

Keep in mind that Dorman offers this product economically ($13) and is usually in stock at any NAPA. Cover & gasket for this price! Prime and paint the unit and use stainless bolts and the results look great!

 

When I changed the rear diff fluid in mine I used the Valvoline synthetic because it says right on the bottle that you can use it in limited slip diffs. And 5k miles later no problem