Retro cars said 4 star was closer to 100 octane. not sure on LRP though. Super/Optimax should be alright.
nice and vague from Retro Cars there...
I recall 4Star was 97RON, while LRP has never actually had an offical RON rating so can be 97or 96RON (possibly 95 but ive never seen it that low). Ordinary unleaded is 95RON, though you'll see other ratings particuly for the Super stuff. Optimax is 98RON.
Only timing needs to be adjusted, all these fuel filters, additives, hardend valve seats etc are a con. Any car destined for the German (probaly other eropean countries too) hav been desgined to run on unleaded since the mid-late 70s. So unless you driving a Trimph, MG or what ever just adjust the timing and switch to unleaded
