In "out of box" finish, World Beater would handle heavy oil better than Ranson Demand.
World Beater is 2000 Abralon, Ranson Demand is 4000 Abralon.
Rg of World Beater is higher, so ball will get down lane farther before making it's move, and will be smoother at the break point than Ransom Demand.
Surface change on either with proper early rollling, or smoother rolling layout will work with either ball for true, heavy oil pattern, but there may be better choices for a true heavy oil ball.
Usually, heavy oil conditions require straighter shots, with lots of roll, rather than stand right and throw left to break point like THS or shorter patterns.