Nice one Valsp---- "it does exactly what it says on the tin" ----------- Just for those who might not be "in the know" so to speak}--- TEL = Tetra Ethyl Lead which is the actual additive used when mixed with Petrol (
https://en.wikipedia.org/wiki/Tetraethyllead )....................whereas Octane is not actually found in your petrol at all but is an anti-knock Rating Value and is a comparison of the fuel under test in the Lab. and the performance of a mixture of Iso Octane ( The very best anti-knock fuel but horrendously expensive ) and Normal heptane ( Which is the very worst fuel for anti-knock )........
https://en.wikipedia.org/wiki/Octane_rating ..........When the fuel under test and the Octane / Heptane mix both show the same knock symptoms then the % of Octane in the mix becomes the Octane Number that you see on the forecourt fuel Pumps...........Incidentally the modern trend seems to show a RON number ie}---- Research Octane Number.............Any of you more, ahem ..."Senior" persons remember "Pool Petrol" ??.....Master Sergeant Bilko could be relied upon to get some ----at a price, naturally !! ....................................
