Hey, I'm new here and I've got a question. I bought my first diesel Ram,a 98, bought it from my father. He had the 100,000 mile tuneup done at the dealer last year, and lost like 3-4 miles to a gallon. He watches his milage like a hawk, it went from like 14-15 to 10-11. Anyone got an answer, the dealer told him that all they did was the normal service, I believe relashing the valves were included.