I was talking to my local cylinder boring/honing expert the other day... and we got to talking about fuel, and how it has changed for the worse over time. At 16 years old he took over a struggling Sinclair gas station owned by his neighbor and ran it for some 10 years... till 1970. I asked him if he remembered what octane gas used to be... and after a few seconds of thinking about it... he was sure that regular was 95 octane, and premium was 105 octane !!... because he used to order tankers full every week. For those outside the US.. our octane numbers are based on the R method plus the M method divided by 2.... I believe Europe uses the R method alone...which put the US's 92 oct. equivalent to Europes 96 octane.. (or close).. I don't know what system of measuring the rest of the world uses.