Do you really need to change the oil?, I'm just playing Devil's advocate here. Options

[VavAlephVav]

Really, aside from the cleanliness and longevity of the motor. How much of a difference does it make on the performance or power output of the motor if you have old burnt up oil that is broken down still in the motor?
Percentage wise how much power do you think you loose from having worn out motor oil that needs to be changed?

10%? 20%? more?

[Bitter]

Well eventually that worn oil breaks down, cokes and causes them to stick in the ring grooves which lowers compression and diminishes performance. Also as the gets worn it looses viscosity and begins to burn more readily which fouls spark plugs and diminishes performance. And lets not forget that excessive oil consumption forms heavy carbon deposits on the valves which can cause hot spots which can lead to pre-ignition that burns holes through pistons and can also burn the valves themselves which leads to very low compression. Oh and of course there's nothing high performance about a sludged oil pickup which causes spun bearings and connecting rods to come out of the block, which could be considered weight reduction but at that point it's not an engine but an anchor and heavy anchors perform the best so...

Just change your damn oil on time. 3K, 5K, 7K, 10K, whatever interval works for you given the type of driving, engine condition, and quality of oil and filter used.