I, like a few others here, do not want to start an argument or controversy, but on MY 7.3, I change oil and filter at ~10,000 miles. That includes severe duty while towing a 10,000 pound trailer up and down 12,000 foot mountains in Wyoming and Colorado. When I first got the van, I followed the maintenance guidelines with oil and air filter, but after doing research, on my own, decided that frequent oil changes are just another way for oil companies to get more of my money; my opinion, not trying to convince anyone. I bought K&N reusable air filters, started using full synthetic motor oil, and used good quality, name brand oil filters. My van is 18 years old, has 143,000 miles and the engine is super strong; my K&N's are over 15 years old and still in good shape. The air filters, alone, over the past 15 years, have saved me close to $1000 in maintenance. And just to clarify, I can afford anything that I want; I'm not too cheap for the added maintenance, just don't see the necessity. Again, my opinion, and this works for me and my vehicles. OBTW, I have 2 vans (an 85 & a 99), a truck, a car, and an RV. I'm the original owner on all of them, and they are all in great shape.