I prefer syn oil, 5w30 as the manual states for a couple of reasons:
1. I personally want oil on the top end soon as possible. These rigs have camshafts that run in plain bearings cast into the head. Ie, the are NO replaceable cam bearings per se. The cylinder head where the cam sits is a very expensive piece of metal to have replaced if the cam gets wiped out.
2. My rig turns over 3,000 RPM on the highway. That alone puts tremendous shear stress on the oil. This shearing of oil reduces its ability to cusion the hammer like blows on the con rod bearings as well as the mains.
3. I have personally seen with my own eyes, a 94 tracker get rode hard and put away wet. Its had nothing but synthetic since approx 30K. It now reads about 180K on the clock, and compression is within 5% of new! Nor does it burn oil. I think this is a combination of good suzuki design as well as damn good oil in there. This is a friends rig that has yet to see a car wash. Mother nature washes it for him.
4. The advantage to NAPA or WIX filters is this. You will see them only in auto parts stores, not big box super cheap discount stores. Thus, they are not sold on price like waldo world likes to do with its stuff. Because it ain't sold on price, there is little pressure from NAPA to push for cost/quality cuts to "make it" in the marketplace. Purolator is a good second, but my money is on NAPA/WIx filtes any day of the week in any ride my friends.
Tim already pointed out what I dug and dug to discover, that these are damn good units, well made, with silcone drainback valves (where applicable). SGP is good too, Tokico makes 'em but zuke also sources from another outfit in Japan whose name I cannot recall right now.
If I owned a Jag or rolls, or a beemer, yes, I would run these very same filters on my ride just like I do my zook.