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Topic	using premium gas when the manual 'recommends' it?
TheSuperSilver 04/05/24 2:09:08 PM #31:	thisworld posted... A good rule of thumb is to calculate the fuel requirement using your engine's compression ratio. Higher compression ratio = higher octane needed. Google gave 9.8:1 compression ratio for your car. That's a really high compression ratio for 87. For comparison I once used 87 for a commuter bike with 9.3:1 ratio. But 87 for 9.8:1 ratio? That's pushing it too far imho. My suggestion? Use 91. Honda most probably mentioned 87 for marketing purpose. Not too mention the use of 87 came with a caveat about knocking and top tier fuel. Knocking is a sign of premature combustion tc; keep that up and it will wreck your engine. The line '87 won't damage your engine' was written in controlled lab condition. 20 years road use like you planned is not lab condition and if you blamed Honda, they'd just say "can you prove that you always use top tier 87? also didn't we warn you about knocking?" They wrote that caveat for legal reason. True about compression ratio - my car's engine is 11.2:1 so 91 octane makes sense. The manual also talks about using less than 91 octane if it isn't available as a short term solution. It explains what the premature knocking is and that the car may experience that but to stick with 91 whenever possible. So "just use sub 91 octane and deal with the premature knocking and engine/fuel performance" is not a responsible solution long term. --- When it is obvious that the goals cannot be reached, don't adjust the goals, adjust the action steps. - Confucius <cite>TheSuperSilver posted [p:979748980] in using prem... [t:80739662]...</cite> <quote>thisworld posted... </cite><quote>A good rule of thumb is to calculate the fuel requirement using your engine's compression ratio. Higher compression ratio = higher octane needed. Google gave 9.8:1 compression ratio for your car. That's a really high compression ratio for 87. For comparison I once used 87 for a commuter bike with 9.3:1 ratio. But 87 for 9.8:1 ratio? That's pushing it too far imho.My suggestion? Use 91. Honda most probably mentioned 87 for marketing purpose. Not too mention the use of 87 came with a caveat about knocking and top tier fuel. Knocking is a sign of premature combustion tc; keep that up and it will wreck your engine.The line '87 won't damage your engine' was written in controlled lab condition. 20 years road use like you planned is not lab condition and if you blamed Honda, they'd just say "can you prove that you always use top tier 87? also didn't we warn you about knocking?" They wrote that caveat for legal reason.</quote>True about compression ratio - my car's engine is 11.2:1 so 91 octane makes sense.The manual also talks about using less than 91 octane if it isn't available as a short term solution. It explains what the premature knocking is and that the car may experience that but to stick with 91 whenever possible. So "just use sub 91 octane and deal with the premature knocking and engine/fuel performance" is not a responsible solution long term. --- When it is obvious that the goals cannot be reached, don't adjust the goals, adjust the action steps. - Confucius</quote> ... Copied to Clipboard!
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