Switched to Syn today.....
 

I swapped out all of my old fluid for Amsoil 75-90 gear oil in the front and rear diff and the transfer case. I also had the tranny flushed with the BG machine and had them install BG syn tranny fluid.

Overall I'm happy with the difference that it has made, seems to shift smoother. Though I did have one question I was only able to get about 2 qts of fluid in the rear diff, is this common? The book called for 2.6.

While I was under there I changed my oil and did a little clean up.

I only had one problem we destroyed the drain plug on the front diff. Seemed like someone put that thing on with an impact gun (I know that you can't really). Ended up getting it off and replaced it with a new one.

When replacing gear oil in any of the components that use it, the vehicle must be level, front-to-back, and side-to-side.

If the vehicle isn't level, you will either get too much, or too little gear oil in the respective component.

Was your vehicle level?.

Yes it was on a lift and level

Bump for some other opinions

If you put oil in up to the fill hole yer fine.