"driving in excess of 15k - 20k miles a yr"?

More mileage per year is far better than hardly any mileage at all per
year. Heres how I see it - If a person puts 100k on in a year and
maintains it, 700k to Million miles wouldnt be hard to reach. If you
live in a moist climate or a region where the roads are salted every
year you will have exhaust, brake lines, and fuel lines rotting out and
looking pretty bad in about 10 years+150k miles. (typical for Ohio cars
here)

Cold starts are the biggest wear factor on an engine. If your usage of
the car involves 5 to 10 mile trips for every cold start then you arent
looking at a engine with a very long healthy life. (tho it may still
run, just not tops)

If you could measure an "engines" life by cold starts alone you "might"
come up with something that looks like this

Miles traveled for every COLD start = Expected engine Life Span

5 miles = 50,000 miles
10 miles = 100,000 miles
20 miles = 200,000 miles
30 miles = 300,000 miles
40 miles = 400,000 miles
100 miles = 1,000,000 miles

This isnt very scientific or accurate but ya's get the idea thats been
brewing in my head...I think.