The only reason for LRP is as mentioned above, Lead Replacement for old engines in some classic cars that used cast iron cylinder heads to prevent valve recession from using ULP - the lead in old lead content fuel was an upper cylinder and valve lubricant essentially. I don't think the "lead replacement" is as good as the old lead content fuel.
Many many years ago when I still drove Corollas and so on, I tested 95 ULP compared to the then 97 leaded and the engine was down on power and pinged easily! I used to mostly fill up with Engen at the time and soon after they released 97 ULP which was a lot better and performance was basically the same as 97 leaded, just no white exhaust pipe of course (miss that). Years later they dropped 97 ULP and I was forced between LRP and 95 ULP - interestingly, the 95 ULP was fine and there was no pinging/performance issues. I did try LRP for a while, but since my car could run on either, opted for ULP.
My '68 Volvo which does of course have a cast iron engine block and cylinder head has to of course run on LRP - still want to have steal valve seat inserts fitted so that she can run on ULP in future...
