Originally Posted by kschachn
is there any technical evidence that a flat tappet engine requires elevated ZDDP after break-in?
Some engines have high valve spring pressures even stock and will need a good dose of Zddp even after break in.
For example the engine in my Ford Escort, it's a SOHC flat tappet Hemi engine, the stock valve springs are 235lbs at peak lift, i therefore refuse to run anythign with less than 1000ppm of Zinc in it, preferably 1100-1300.