does reg. unleded + octane boost = supreme unleded

[Ancient Sledder]

^^^^^ Up north we can not buy 85 octane. Our lowest is 87. I have used 85 in the truck when in the US and it did not bother it.

 

[Iron Horse Racing]

The enigine was tuned to run on 91 octane, if you run the lower octane fuel in it you may experience lower detination as a reslut if run alot or under heavy loads you can cause excess build up in the cumbustion chamber....this can have serious effects over time.....a tank or two and not heavy pulling not a big deal....You will probally notice a decrease in throttle response .

It's the same in 4 stock engines the major diff ever hear a four stock that should have 91 octane ping on 87....improper detination....