Proper grease for urethane bushings

Is the proper grease for my urethane shackle bushings supposed to be synthetic or silicone type grease? Seems as though I remember something about standard chassis grease breaking down the urethane bushing material. I think I am due for a greasing. Also best place to purchase. Hopefully at my flaps. Hate to have to mail order it

 

It's supposed to be syn. Quadratec carries the correct stuff and I think the little hand gun for it. I haven't heard anything about ruining the urethane but it will squeak after a while.

 

Thanks Rit.

 

John: Just saw this thread. I bought the Qtec gun and grease and it works fine. Then I realized it was nothing but silicone grease, so I went on e-bay and bought a bunch of gov. surplus tubes of GE silicone grease for a fraction of what Qtec sells refills for--will just squirt it into the old tube. R)

 

Tried fidning it on ebay but couldn't. Was hoping to get some locally. As long as I know synthetic is ok to use too, I'll just buy some at flaps.