You're really supposed to change the oil EVERY 3,000 miles OR every 3 months, whichever comes first.
You could run synth for 2 oil changes a year, that's what I do.
So for starters I would change the oil at least twice a year, and run synthetic.
On another note high performance stuff isn't for show and tell, you really have to keep up with your car's standard maintenance first or you're as well off throwing your money in a shredder. Putting high performance stuff in a car that's so far out of date on regular maintenance does absolutely nothing.
So the rest of the vehicle likely needs a 500-1000 dollar tune-up as well, depending on how often little or nothing got done. You can throw that garbage K&N filter away and do yourself a favor and replace wires and plugs and cap and rotor and breather cap and pcv valve and fuel filter, that'll likely make a change vs. throwing ONE little high performance item under the hood and expecting a miracle.
A FE gauge should be standard equipment in every vehicle.
I have a 96 mercury sable with 4 wheel disc brakes and have experienced more than once dragging front and rear brakes due to caliper slide pins that were rusted or hung up.
Also, I would be driving the vehicle with cardboard blocking the radiator to warm up the engine quicker and disconnect the air intake snorkel in the left front fender that is sucking cold air into the engine.