I recently bought a 2004 Marauder, one owner with 80k miles. It seems to be using oil about 1 quart every 2500 miles. The last oil I used was Mobil 1 5w20 high mileage. No leaks that I can see anywhere. I was thinking of going a bit thicker to either Mobil 1 10w30 or 10w40 high mileage to see if I can slow it down a bit. I also have access ( for free) of Delcac 1300 15w40 or Rotella T 5w40 but I see that these aren't rated for gas engines anymore. I live in Northern Va, it gets cold but nothing crazy. What would you use ?