I have a 95 Ford ranger 3.0L 4x2, has a slight leak in rear diff, was going to replace the gear oil, was wondering what kind to use? 80-90 seemed the most common on 98+ rangers. And if it's easier to find a new gasket or to just replace it with RTV

 

Welcome to the forum

Look on the drivers door label, back of the door, at the bottom of the label you will see AXLE, under that is a number, if its a letter and number like R6 then you have a Limited Slip(positraction) rear axle
If its 2 numbers like 96 then its OPEN style, most common
Info here: https://therangerstation.com/tech_li...le_codes.shtml

If its Limited Slip(L/S) then you have to use gear oil that has Friction modifier added, or add it yourself to regular gear oil, 4 ounces is needed

Yes, 80w or 90w is correct for all Rangers except for FX4 Level II with Torsen differential

Found this how to: https://therangerstation.com/tech_li...leFluids.shtml

 

Yeah it actually is R6, so 4 ounces of the limited slip additive and fill with oil until its full? Also is it better to replace with a new gasket or just use RTV?

 

Up to you on the gasket, there should be no pressure inside the different housing as it is vented, you can check that vent hose is clear and small filter at its end, under the bed, is not clogged, vent is on one of the axle tubes

If you use a gasket I would still use RTV on both sides of gasket