I have heard of quite a few over 100,000 and still going, but no one I know personally to verify that. I don't like the idea of aluminum cyl even if they are T-6 (used to use T-6 building liquid oxygen trailers in our barn, and it is very tough stuff) All that ever comes to mind are the Chevy Vega aluminum blocks that were crap. Aluminum cyl are fine if sleeved , better even maybe since the aluminum disipates heat very well.
