I wonder if anyone makes a little chemical doohickey to hook on your oil line to check the chem makeup of the oil (pH level, metal level, conductivity, etc) so you could know when to change your oil without having to send a sample to the lab (5$). i bet it could be done w/ somethign akin to the tester on your duracell batteries but more reuseable.

it would also be nice to know how worn out your filters are... maybe something that could measure the mean particle size, or pressure before filter vs. pressure after filter. As the filter became more clogged the pressure should start to drop off after the filter (full flow). I am not sure of the characteristics of the bypass, but the reccomened change interval is One for every Two full-flow filter changes.
If I was a mech-E or an chem-mech student that'd make a good project.

Jay