[Ishler]

Pete
Synthetic is what comes from the factory. The limited slip in our trucks does not use clutches so be sure the DON'T add any additives. I get the shudder occasionally with or with out the trailer on sharper turns when applying power, more noticeable when the road is damp. Now all that being said be sure the u-joints in the driveshaft are good as they can cause vibrations when they start to wear.