My step van has a sticker that says "extremely important: change oil every 2,500 (3 months) or 5000 miles (12 months)."
I am not sure i quite understand this - how could it be extremely important to change oil every 2,500 miles (where as usually i hear people changing oil every 3,000) but then also be ok to go 5,000 miles if the vehicle gets less use?
Is 3,000 miles an safe interval for oil changes?

Also, i have a standard stp oil filter - does this need to be changed with every oil change as well? I have heard some cases where it does not, but not sure how it applies to this engine.

thanks,
Paul

I change the oil/filter in our 6.2L close to 3,000 miles or as practical. As practical occurs when we are on a trip and the weather is bad or a location is not readily available. I change my own oil and filter which I carry with us.
STP filters are not the best quality. I would use Purolator Premium 1, NAPA Gold, WIX, or Mobile 1.