You didn't buy the $60 spray pack did you That's enough triflow for you and your children and their children and all their friends!!! The spray pack is built for bike mechanics who do 20-30 bike services a day. It saves them time I guess.

Anyway, the store dude's method will werk. But make sure you always clean as much of the old stuff and embedded road grit out of the chain, cluster, and jockey wheels before applying a new coat. It seems to get cloudy and stickyish when wet, so spend extra time cleaning after playing in the rain.