Applying grease to the damper plates generally slows down rear pod movement. Apply it to control rear traction and to make your car flip over in the corners less.
Generally: thicker lube in the damper discs means more rear traction, so also less steering. Keep in mind it's all about traction management , not getting the most traction.
As a general guideline: Start with fairly heavy shock oil, and work your down to the point your car starts to roll over in the corners, then go back up a weight.
I use Corally damper syrup, so I can't tell which shock oil weight to start with. On intuition I'de say 40wt should be a good starting point, but correct me if I'm wrong.
When you have your car stable enough to avoid rolling over in the corners, it's time to start playing with things like front springs and the amount of traction compound you use on the front wheels. (start with a small line on the inside of the fronts).