There's nothing wrong with Tesco momentum.
The difference between supermarket fuel and name brand fuel? Additives. The major component of the fuel is identical. Name brands are spending a fair amount on developing new and improved additives that keep things clean, lubricated, emmisions free, anti-knock, anti deposit, anti sludge or all manner of other things, but it's an game of ever decreasing returns. They're rapidly being overtaken by engine manufacturers who are achieving the same things through control systems engineering, and genuine breakthroughs in the chemical engineering side are now few and far between.
Go back in time a few years and there were big differences. Engines ran so badly from factory fresh that often the only way to get them to perform in any way decently was to load the fuel with additives. They'd get coated with carbon deposits, require regular rebuilds, and generally be hard to start from cold. Additives helped keep carbon under control, assisted cold starting, and increased knock resistance. It was worth getting decent fuel. Remember RedEx? My dad used to add a shot of it to every tank. Developments such as direct injection have negated many of the advantages of high price fuel, whose cleaning additives would keep inlet valves free of gunk introduced by recirculating oil breathers into air intakes. Direct injection sprays the fuel directly into the cylinder, so it no longer gets the chance to clean the intake valves etc on its way in.
The worst additive was tetra ethyl lead (TEL). Rather than design engines properly to run without knocking or using freely available and very cheap ethanol to achieve the same ends, the manufacturers and patent holders lobbied the oil companies to add TEL, since it was simpler and cheaper than designing engines properly, and a very profitable move for DuPont, the patent holder. Of course it pumped billions of tonnes of highly toxic carcinogens and neurotoxins into the air as by-product, lowering IQ's and introducing behavioural defects in children, killing several factory workers who made the stuff, and leaving us with lasting damage to the atmosphere, but apparently this was acceptable in the 20th century. Of course manufacturers claimed it would be impossible to retain efficiency and performance without TEL, until they were forced to do it when TEL was banned... History shows us that engines have become ever cleaner, more efficient and more powerful, and that motor manufacturers have always been duplicitous lying ********
Interesting point of trivia, the same guy who brought us widespread use of TEL and the resultant environmental calamity, stupid children, and widespread lead poisoning, Thomas Midgley, also brought us CFC's... I doubt that there's any other single individual in all of history who has managed to create quite so much damage all on his own...
) so I'm back on Esso Supreme now, slightly better MPG and I can rest assured it's Supreme.
