As per title,

my L300 has a major smoking problem only on start up. I've added "Stop Smoke" to my engine oil, and the smoking has stopped, however, I know its not completly fixed.

I thought it was my piston rings, but someone was telling me something about a "diaphram", which stuffs out (apparently a common thing with the cyclone engines), and needs fixing/replacing.

Does anyone know where this diaphram is located? or have a more depth explination as to what the problem might be? the guy that told me, wasn't 100% sure on how to explain it, but he basically said that petrols thinning out my oil, causing it to smoke the way it does.

The engine has done 300,000 k's, hence the reason I thought it could have been my rings

thanks in advance.

Smoking on start up is either worn rigs or valve stem oil seals. Chances is its both as you've 300000km on the clock. Very common and not difficult to fix if you're mechanically minded.

The "Diaphram" referred to is in the mechanical fuel pump on 4G63 Carburettor models. The fuel pump is considered to be non repairable and a new replacement should be sought and fitted below the carburettor and inlet manifold.