The illusion isn't really a heavy oil ball, but I have similar balls in a reactive version (same RG/Diff.) and its a very controllable, strong midlane reading ball. It would work better as a benchmark ball convering mediums, anywhere between med-dry to med-heavy.
For a true heavier oil condition, the Epic Quest is the strongest cover ball you will find in the rotogrip line, and a step below that will be your SD-73 Classic and Epic Odyssey. Below that will be the Saga, Horizon Solid and Illusion. Hope this helps,
REvans284
Edited on 11/29/2007 4:05 PM