The list is now

1) Sticky rings => leading to bore / piston failure => excess blow by => run away engine
2) Varnish formation => fuel blockages => IP damage / lift pump failure(?) / Injector blockages
3) Engine oil contamination due to unburnt varnish
4) Unburnt liquids can cause damage to vehicles with catalytic converters

To my mind this boils down to two problems

a) Fuel purity => filtration / water content / cleanliness
b) Fuel combustion

Does that sum it up?

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!