Mixing 98+ octane fuel with 95

[EVR]

So far I always refilled my car with 98 or 100 octanes fuel.

I am just curious if someone know what is happening chemically if, say, you top up a 100 octanes half-full tank with 95: does it became 97.5 octanes? Does the 100 "contaminate" in a good way the other fuel bringing it up to 100? Nothing?

[cayman-black]

Nothing except your V8 will be 1 second slower around those swiss alps.

[bogie]

Yeah...pretty much averages out....but if you read the advice of the fuel companies they obviously tell you about all the other good stuff they are adding to the high octane that you dont want to be without and recommend you should stick to that..and of course if it says in the fuel flap to use 98 then thats what we tend to do.

Thread here on which fuel, watch out for ethanol laced fuels

https://www.pistonheads.com/gassing/topic.asp?h=0&...

https://www.hemmings.com/stories/2014/04/11/tech-1...

[EVR]

cayman-black said:

Nothing except your V8 will be 1 second slower around those swiss alps.

bogie said:

Yeah...pretty much averages out....but if you read the advice of the fuel companies they obviously tell you about all the other good stuff they are adding to the high octane that you dont want to be without and recommend you should stick to that..and of course if it says in the fuel flap to use 98 then thats what we tend to do.

Thread here on which fuel, watch out for ethanol laced fuels

https://www.pistonheads.com/gassing/topic.asp?h=0&...

https://www.hemmings.com/stories/2014/04/11/tech-1...

Thanks.

I am not trying to advocate (or not) 98+ fuel, just trying to understand the chemical reaction (and eventually the car's) between two different fuel types.