There's lots of Redex products around there's days, Injector Cleaners etc, but they still offer a Lead Replacement/Upper Lubricant; it's just not as readily available as the stuff aimed at the more modern motors.
If you look at Fleabay, there's lots about, with various labels, some stating part number RADD1301A, others listing RDX18, with many not saying which they are...
This one even claiming both numbers!!
https://www.ebay.co.uk/itm/RADD1301A-RD ... SwdEhdC40F
I contacted Redex (Holts) and the prompt reply was that RDX18
So if you are buying Redex Lead Replacement, you might want to bear that in mind.ceased to be a product in the portfolio more than a handful of years ago – we wouldn’t advise using any stock that is stamped RDX18.