I suspect when mileage is taken into account in terms of the distance travelled relative to time, in terms of the age of the machine. i.e. It seems possible that a 20 year old regularly used (in the manner Ewan suggests) and well maintained classic with 100k miles on the clock, might be found to be in far better condition than a 5 year old similar example of the same marque with a mere 4k miles covered...?
There is little doubt that this is the case. Apparently some police cars are in very good nick despite the use they are put to because the engine rarely gets cold and its warming up from cold that most wear occurs. A pal has the same model Ferrari as mine but the mileage in 20 years is north of 150k ( I think 180k) yet the engine is sweet using no oil and if anything more mechanically quiet than my car at 21k miles.
Oil drain from the top end is the issue. I had a Stag for 30 years, didnt use it much at all but kept periodically starting from cold in storage in the belief that was good for it. It wasnt. The cam bearings farthest from the oil pump failed and since these ran in the head line bored ( ie no shells) it was a head replace job.
