Since the stuff has a high TBN level (12), it "should" be able to last quite a while and not need to be changed as frequently as oils w/ lower TBN ratings.
And, at $10 a quart, I'd hope it wouldn't need to be drained as frequently, either.
Good ole Amsoil .... ...and their marketing BS ...
WHERE do they suggest that the combustion by-products GO ... that are in their oil vs staying in the other brands ?
10$ a quart ? .... that is due to their multi-level-sales and marketing program that has so many hands-in-the-pie.
...and their marketing BS ... 
