Good decision on the conventional 10W-30, that can save the seals from starting to leak But on a stock TJ engine I would NOT waste my $$$ or time adding more zinc to what's already in the engine oil. Yes the industry was forced to reduce how much zinc is present to prevent damaging the catalytic converter but it's not so low that it causes engine damage to a stock TJ engine. There's not even pressure on the cam lobes from the factory valve springs to cause damage as evidenced by the severe lack of complaints of valvetrain damage in our TJ engines. If I was running a high-performance race engine with a high lift cam and stiffer valve springs I'd definitely be adding additional zinc but I'm not so I don't.