I put my balls into the kitchen oven every couple of months, just at lowest possible temperature (50-70° C). The balls are put in for 10 min, warm up gently and start sweating. After this time I wipe the ball with a micro fibre towel. I repeat this procedure as long as there is no more significant oil/dirt oozing visible. Then I let the balls cool down gently and clean them with a special plastics cleaner (professional stuff, for window frames) or Mr. Clean Orange - both work very well. Thereafter, the surface of the balls is tacky again, on matte balls I sometimes apply some wet pad sanding to rough up the surface and clean the track.
Hmmm, I wouldn't expose a bowling ball to bright sunlight for longer periods. UV light corrupts plastic molecules over time (that's why plastic car fenders get light blotches). This may sound a little bit "panically", but sunlight will make the material brittle over longer periods and bleach it.
The dish washing machine sounds very good, too (do not have one...).
And cars' luggage spaces in the summer are alo a great place to make balls sweat.
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DizzyFugu --- Reporting from Germany
"All that we see or seem, is but a dream within a dream..." - Edgar Allen Poe
