If it's in good condition, I am jealous of sphillips' 2000 with only 77K on it. I use K&N air filters on all my cars/trucks - 2000 and 2011 Expedition, two 2005 (4WD & 2WD) Explorers and a 2008 F150. From experience I think the K&Ns gain me about 1 to 1.5 mpg depending on the engine (5.4, 4.2 or 4.0) and since I generally keep vehicles until they die, the K&Ns save me money over buying paper filters. I clean them every 25K. It is not terribly convenient to clean them, let them dry and re-oil them, but I'm accustomed to it. Stay with paper if your time is more important than a little savings - but I probably would have bought 11 paper filters for the one K&N I've had in my 2000 Expedition. I keep the old paper ones around that came with the vehicles in case someone needs to drive it while I'm cleaning the K&N. The few times I've every had a issue with an K&N, K&N replaces it immediately. For oil filters I've been alternating between K&N Wrench Offs and Wix XPs. There are a few things I like better about the Wix XPs oil filters over the K&N Wrench Off filters - like the XP using a tension spring instead a leaf spring and the XP base plate having 8 flow holes instead of the 6 on the K&N. I have found that there's about as many opinions on oil and oil filters as there are brands, so my opinion is just one of many.