I have a JD tractor with an 18HP Briggs twin. Oil filters have really gotten out of hand for this engine. Dealer wants $11 now ($6-$7 the last 5 years). The NAPA/WIX is also $11. The Purolator, much to my surprise, is also $11! I only run my tractor 35 hours a year. Manual says 100 hours. Would it be safe to change the filter every 2 years? I am kicking myself. I just placed an order with Fleetfilter a month ago and forgot about my tractor! Could have added the WIX for $6.20 or so.