[Sylak]

I own a 50+ year old cultivator that I am trying to get going again.
Its a two stroke, and the printed information is one part Castrol XL (SAE 30) oil mixed with 24 parts petrol.
My question is; should I bother trying to integrate a lead additive or not bother with it.

[grendel]

The proper answer is probably yes, but it all depends on the valves, and whether the seats are hardened or not, - the lead in the petrol was used to soften the impact of the valves against the valve seats, and stop them wearing out.
Now if you are willing to risk the valves wearing (I mean we aren't doing high mileage with a cultivator are we- unlike a car) then you could just run on unleaded, other than that would be a lead additive or one of the types that a pellet sits in the fuel tank that provides the lead.
Grendel

[JayG]

I was faced with either buying lead additives or having special hardened valves and seats fitted to my MGB engine (so I got rid of it, although it was unfortunately falling apart at the seams anyway!)

Think Grendel may have missed Sylak mentioning that his cultivator has a 2-stroke engine, which has no valves, so hopefully does not need leaded petrol (bit on the ragged edge here - don't quote me!   )

[R Tallentire]

Two strokes never needed the lead aditive because they don't have popet valves, and compression is fairly low due to losing a bit of the "compression" stroke before the inlet and exhaust ports are closed off. In fact most small garden machinery engines are low compression, and the four strokes with aluminium engines already have hard valve seats fitted. I've been using unleaded in my cast iron block Suffolk mower since leaded went off the market with no additives, and no problems so far.