Well at 90k my head gasket went, depsite always having decent coolant mix and never been cooked. Also head gaskets are defo a common occurence on these engines, but not really any worse to comparable all alloy 16v engines. Rover K-Series, Vauxhall XE etc both highly rated engines, K-Series love head gasket also and Vaux XE cylinder heads go porous after so many miles, so I would say F7 engines are pretty much par for course, at least half will need a gasket before 100k (some even when looked after) and I bet a wee survey on here would prove this. But thats only one wee probelm, rest of engine is suppossedly bomb proof, especially bottom ends. Also spray bar helps bores last almost indefinetly!