Friction Modifier

[jjjje2007]

I changed my rear differential fluid a few months back and added the friction modifier, but since then I have learned that I don't have the LS rear diff. Is this going to be a problem or should I change the fluid again? Over the last month, I have replace three of the four wheel bearing, so my 2002 Mountaineer rides alot smoother, but now I am noticing a vibration at 65 mph. Can the friction modifier cause this?

 

[Limited02]

I doubt it's a problem or will hurt anything. If you feel the need to change it, then go for it. Another thing is make sure your tires are not out of balance because that could be causing your vibration at highway speeds.