I have a 94 f-150. code 19 rear axel, what kind of gear lube should i use? is any friction modifier required with this, i dont think it is a limited slip

 

piperc,there should be a tag being held in place by one of the differential cover bolts.What does that tag read? I think code 19 means it is 3:55 gears,and it should be a 8.8 differential.The tag will most likely read;
3L55-L meaning limited slip.In that case you will need the 4 oz. bottle of friction modifier from Ford.Or;
No "L" means an open differential.These do not require the friction modifier.
I use to own a 93 F150 with a 3:55 open differential and used regular old 75W90 gear oil.BTW,if I were you ide go back with a gasket on the cover.Any good parts store that sells FelPro gaskets will have one.Here is the part number;
RDS-55431

 

Thanks! although i just got in from doing the job, it feels good to know i did it right. although, i used exxon 80w90, i dont think that matters too much.

 

Piperc

code 19 is a open diff not a limited slip diff.

I did some research for my own 97 with that diff since the owners manual is more than a little vague in what to use.

After much searching I found Ford Motor Craft Oil that meets the spec. listed in the owners manual (@ $20 a qt) it is a Synthetic 75W140 Gear Oil that meets the GL-5 standard. No Additives are needed.

I've found Royal Purple at under $10 a qt online that meets thoughs specs so I've went with that.

Doug