I don't think you can accurately come up with a reasonably accurate $ number. No two 10 year old DPs are alike. It would depend a lot on how it was taken care of the prior 10 year period. I'll try to give you a number that reflects my 14 year old DP and 80,000 miles of fulltiming.
Regular service to the oil change intervals, some I did myself. As I get older, I have it done once a year. Appx $200.
Repairs?
One fuel pump and a 90 mile tow. Coachnet provided the tow free and the pump was $530.00 two years ago.
Engine fan self destructed last year in AZ, 7 mile tow (again free) and $2930.00 for fan, AC compressor, belts, new radiator hoses, fan pillow block and bearings an installation.
$310 four months later to have the fan removed, turned around the correct way and reinstalled to correct the overheating problem caused by the Willie Lumplump mechanics installation 4 months earlier.
New tires 4 years ago, $2650.00.
I know of no pending repair or PM needs going forward. I feel my chassis is sound and reliable at this time.
hershey - albuquerque, nm
Someday Finally Got Here
My wife does all the driving - I just get to hold the steering wheel.
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Expedition - Chevy Equinox