Cheers, good stuff.
I've been running my engines on diesel engine oil for about 10 years now. They have higher zinc content than normal motor oil, and also has high detergent- the engine is absolutely clean after 3 oil changes... I mean the aluminium inside the head is silver instead of the ugly brownish color.
The problem with zinc with a newer gas cars is when the zinc passes the combustion chamber it clogs the cat and the o2-sensor.
No really a problem though, as if your engine is healthy, blow-by should be minimal, and o2 sensors are cheap...