Suzuki Repair: better gas mileage, oil viscosity, good mileage

Question
Hi,
It seems to me my 91 Tracker/sidekick is not getting as good mileage as it used to.  Any tips on what can be done to help it run more efficiently?

Answer
The most common things are tune up items including valve adjustment(every 30k minimum)  oil viscosity (15w40 will lower your mileage compared to 5w30) Tire pressure, and type of tire will have a considerable effect.  If you use large off road or snow block tread, you can have a 3-5 mpg drop.  The high tech platinum plugs(bosch +4), K+N filters, will have a small effect, however monitoring your driving habits, and where you drive is equally important.