I'm wondering why. The Evo backfires frequently at downshifts and these backfires are really loud. I never had a similar problem with other gases I used, including Esso 91-octane. Most of time I use Top Tier brands only. Today I went to a rural part of the town so I filled at a non-Top Tier gas station.

My guess it that the Husky 91-octane actually has a lower octane rating or something. I may have to refill the empty half to the tank with Petro-Canada's 94-octane if these loud backfires keep happening.

 

probably no additives get some octane booster from an auto parts sore I like lucas I think it's called - red bottle -toss that in and don't use that going forward.

 

Thanks for the input, my friend. I will do and won't use that going forward.

 

Why would back fires be related to octane rating?