Excess motor oil changes represent an absolutely huge waste of resources and are detrimental to the wealth of an individual.
Changing every 5k at $25 versus changing every 10k at $25, over a period of 15 years, 300k miles, at a discount rate of 10% and inflation of 3% results in a net present value of $1370, or a net future value of $2135.
$1370 present dollars is a nice chunk of change towards other maintenance on a car that would make a more meaningful effect on the car's overall economic operating life. For the average motorist, changing transmission fluid more regularly comes to mind.
To those who say, 'cheap insurance', try collecting on your 'insurance' policy when your vehicle is totalled or when everything else but the oiled parts in the engine are worn out .
Leave the writing of insurance policies to the trained actuaries, and the motor oil changing recommendations to the engineers who actually design the engines. Each are masters of their own domains.
[ March 04, 2005, 05:23 PM: Message edited by: pitzel ]