i have used powersrvice products, in the winter. I got along fine. only used the 911 to help out others that weren't prepared. I usually mixed a little heavier than recommended, cause ya never know, it might be -40 in the a.m. I never saw the $$ benefit to using it in warmer seasons. As with all anti gel additives, you want to put it in tank, then fill with fuel.
Isomade- dido on the Lucas stabilizer and transmission additive too.