Winnipesaukee Forum - View Single Post

CaptT820 · 08-23-2016, 09:10 AM

The oil industry would like you to believe that higher octane gas makes your engine run better, this is mostly a false claim. Some engines actually do require higher octane gas due to combustion ratio only. IF your car has a combustion ratio of 9.5:1 or lower then you do not need anything above 87 octane. My old Honda civic would even run on 86 octane if you could find it. My BMW has a combustion ratio of 10.1:1 and requires 89 octane. The only cars or engines that require 91 or 93 octane have high compression ratios or turbochargers.

For boats we are spoiled due to most of the marine gas being 92 octane and it also contains no ethanol (a whole other topic for another thread). The marine gas is only a 20% premium over pump and is worth every penny.

The 600-feet altitude it will have almost no effect on gasoline combustion. The air temperature will have much more of an effect at this altitude. You need to be at 3000-ft altitude or greater before the air pressure has an effect on combustion.

08-23-2016, 09:10 AM	#3
CaptT820 Senior Member Join Date: Mar 2012 Posts: 122 Thanks: 86 Thanked 46 Times in 27 Posts	Premium Gas The oil industry would like you to believe that higher octane gas makes your engine run better, this is mostly a false claim. Some engines actually do require higher octane gas due to combustion ratio only. IF your car has a combustion ratio of 9.5:1 or lower then you do not need anything above 87 octane. My old Honda civic would even run on 86 octane if you could find it. My BMW has a combustion ratio of 10.1:1 and requires 89 octane. The only cars or engines that require 91 or 93 octane have high compression ratios or turbochargers. For boats we are spoiled due to most of the marine gas being 92 octane and it also contains no ethanol (a whole other topic for another thread). The marine gas is only a 20% premium over pump and is worth every penny. The 600-feet altitude it will have almost no effect on gasoline combustion. The air temperature will have much more of an effect at this altitude. You need to be at 3000-ft altitude or greater before the air pressure has an effect on combustion.