My brother has an '88 hilux with a 2Y and friend has a 4x4 with the 3Y. Neither of them need to run the valve additive. Looks like the 3Y would be better than the 18R in terms of fuel used. I think they're both 2 litres, but the 18R is slightly more horsepower. Still, if your engine is stuffed, and the new one comes with a 5-speed gearbox, that's what I'd choose. I hated the 4 speed - thirsty on the highway!