My rearend whines real bad and on the bottle of Lucas oil stabilizer it says it stops diff whines and that you can have 100% of the fluid in your diff be the Lucas stuff. Does anybody use this stuff in there diffs? and will it damage my diff if i have 100% of the fluid be lucas??

 

Lucas oil stabilizer is good stuff; previously I used some in an older vehicle to combat an engine oil leak. The stabilizer acts like a "clinging agent", keeping the lube together and climbing. Personally, I would not use it 100% in an axle application because you need the GL-5 additive that is in gear oil. GL-5 protect the gears (mesh between the ring and pinion where extreme high forces are exerted) with a layer of protection (GL-5 film) that will resist the wear from the sliding forces created between the spiral/bevel mesh of the ring and pinion.

If you don't believe GL-5 additive works, drain and refill an axle with 30W or 50W engine oil and drive for 1000 to 3000 miles. The gearset teeth will become very shiny and accelerated wear will progress as time go's on.

 

I use the stuff regularly. I've never had a whining problem, so I can't tell you if it quiets whines, but it does do a great job of quieting gear chatter and bearing growl in manual transmissions. I use it 50/50 in transmissions and 80/20 (20% Lucas) in diffs unless the diff is limited slip, then I run just gear oil with the L/S additive. I don't know how the Lucas will react to the clutch packs, so I just don't take a chance. Otherwise I highly recommend the stuff.

 

My brother is a diesel/gas mechanic running a big shop. When I put a all new diff in my truck he said to run full synthetic in the case (with no mention of any other product to be added )for that application. ken

 

I put some Lucas in my rear diff along with synthetic Valvoline diff fluid a couple years ago and it has done good. My truck has 146k on it.