4500 miles between oil changes still sucks my 13 will go 14,000to 16,000 if I let it. I've settled at 10,000 miles oil is still clean and has NO Fuel in it as per my oil sample tests. Cash the truck out while it's worth something and get a 13 or newer with the DEF system and be happy. There are a few good deals on some lightly used 13's....