CW and balance Cost per mile= $250 x 150,000 miles = $.00167    200,000
$0.00125

Here is the cost for upgrades VS  mileage per cost driven
$1500 of up grades x   200,000 miles = $0.0075 per mile
$2000 of upgrades x    200,000 miles = $0.01 per mile
$4000 of upgrades x    200,000 miles = $0.01 per mile
$10,000 of upgrades x 200,000 miles = $0.05 per mile

When you look at the increased engine life potential of using the upgraded
parts vs. totally stock the OVERALL cost are SMALL per mile.  A stock engine
can last a long, long time.  BUT if you are going to push more power, you are
going to need to make changes to make it live as long or longer.

Robert