Hello, welcome to the forum; 1850s
and Sprints are fine on unleaded fuel as the valve seats must, by default, be hard enough, anything softer wouldn't expand sufficiently to stay put in the surrounding aluminium of the head. People who claim that "
conversion" is required are talking through the wrong hole.
Originally designed for 4-star fuel in terms of the octane requirement, you may find that (95RON) Premium is fine, but if it pinks, either use Super (Shell VPower is, at 99RON, the equivalent of something between 4 and 5 star) or retard the ignition by a degree or two.
