Are there any mileage guidelines to go by when replacing parts that you need to change?
I need to know about when to change the fuel filter, hoses, belts, etc.
Also, on a gc8, what parts should you replace with OEM, and what should you modify, like spark plug wires?

for general maintenance, oil & filter every 3k. timing belt recomended in the book at 60k, however 100 is a better mark. that is unless you are getting an oil leak. oil pump seals often go bad from 60 -100k miles. and the seals and belt should be replaced at the same time. spark plugs are platinum and are rated for 60k miles, though replacing them earlier won't hurt. fuel filters should be done about 10-15k miles. you can check it yourself by blowing through post filter nozzle w/ it removed from the car. if its very hard to blow through, or comes out brown or dirty change it. and try to get a direct subaru replacement. belts just keep an eye on them. have them checked at service time. something not too many people think about is getting their coolant flushed. old coolant can actually start to break down seals and hoses. i think those are recomended every year to 18 months.

PJ

go to mysubaru.com and setup your account. in your owners manual and online have a guide on what and when to do. spark plug doesn't do you much. stocker is fine. :)

You can pick up an info manual (it is a part of the Factory Service Manual) for your car from subaru. It will have the schedule and will even tell you how to do most of the small stuff. It will have most of the measurements and capacities plus a lot of other info.

It only cost me about $20 and has paid for itself a couple times over. It is normally Book 1 out of several.