Yes i remember the rover days and 5*too, so from the above, we have about 90% of us are 45+ and one who has only run Optimax in his life!

Should add that the Rover V8 is about the best engine ever made available to the UK for volume and specialist cars.
Other than the Cross-Flow, surely the very best powerful and light engine around?

Graham

that was never an issue per se in UK until 1975 US EPA clean air Act especially California- leaded was phased out quite late I believe 1993- but a quick look said 1999 in UK, and 2002 Australia. According to UK politicians enquiries it wasn't so much of "think of the children!" with requisite pearl-clutching but more higher octane or "higher aromatics" were more an issue of cost of production see api.parliament.uk/historic-hansard/commons/1973/nov/05/five-star-petrol.
Worked on every hot British car during the 1970s when a trickle of Japanese were coming in with their total lack of choleric oil eruptions and their willingness to start every turn of the ignition and non random quality and finish. Tricksters they were. What's the fun of a car or motorcycle you don't have to occasionally reassemble?

Interestingly, Japan Premium has RON of 100 Octane. I you want five-star fun- use AvGas. Rebuilt a Jaguar XJX XK engine 4.2l to run on unleaded, owner unhappy with performance- unsurprisingly unwilling to part with money for "ÿobbo" (his words) aftermarket mild-cam and better fuel delivery. Took it to rural airport- gave man money- filled up car with AvGas- very fast. Did the same with a P5B, very conservative owner- was annoyed at his lay-buy one-sided payment arrangement- decided to prank him- went rural airport- give money- get fuel, accidentally lost a note maybe yellow coloured paying for fuel. PIcked u owner got him to test it- I don't think he'd had such a thrill since his honeymooon.