In general, (I thought the fear factor was sort of a dud).
I'd move on and buy a real oil ball like a Reaction Roll, Reaction ARC, AMF Triumph TNT, Vortex Particle etc.
But as far as differential it is the ability of a ball to flare! Coupled with strong flip blocks it is the ability of the ball to turn the corner and drive from inside.
Balls for heavy oil and for lighter oil can both have high differential.
For example a Vortex Particle for oil and a Jungle green(.60 maybe) for lighter both have good strong diff over .45!
I find if I take a low differential ball, (under .30) and drill weak it in general seems to have the ability to not really grab in the midlane and sort of break free, or go beyond the break point.
Balls with too much differential coupled with too strong a drilling and a good amount of hand seem to on the other hand have too much midlane and burnup.
A great review and example of this is this wonderful review by a very good bowler and well respected member of ballreviews. Chris of buddies proshop re the high diff triple XXX factor, (diff of .58).
http://www.ballreviews.com/Reviews/Reviews.asp?ManufacterID=11&BallID=499&ReviewID=20558Hope this helped a bit.
REgards,
Luckylefty
PS as a medium handed player for most conditions I see, (Not extreme dry or extreme oil). I find the general rule: Drill your weak balls(low diff) strong, and drill your strong balls(high diff) weak. Only for extreme dry and oil have I found that it makes sense to put super strong drills on high diff balls or weak drillings on weak balls. And for most conditions it just makes them unusable.
Remember this too! Low flare balls with weak drillings are good for very strong backends(no oil in back), high flare balls(high diff drilled strong) with stronger or strong drills are good for extreme carrydown. (as flare is defined as exposing a new layer of dry surface to the lanes).
