I too use NAPA filters with Mobil 1 since 2002 on all five of my sportsmans that I have owned (currently a 2005 and 2004). NAPA filters are top of the line - made by WIX.

 

AMSOIL 0w-40 for the engine. Polaris lube for the tranny & front differntial.

 

mobile 1 0w-40 oil. aftermarket filter like a fram is what i use on my new one.

 

I'm about to do a full service on my '05 700 EFI and am going to use Amsoil 4-stroke 0w-40 synthetic engine oil with a Wix filter, and the proper Polaris fluids on the front and rear gearcases and transmission. Polaris indicates that any GL-5 80w-90 gear oil is fine for the rear gearcase, however. I have yet to find a substitute for the hub fluid for the front gearcase and am not sure what, if any, ATF will work in the transmission.