Trip fuel mileage

[snoman]

I recently had to make a short notice trip to South Carolina for a few days to visit a sick relative and drove 1200 miles in 3 days. It was 560 miles one way and I was able to make it down there on one tank and back as well will a full tank at start and get some good accurate MPG numbers for my 89 4x4 burb. Going down we got 17.2 running 70 to 75 at times and coming back we got 16.7 running 75 to 80 a good bit of the time because it took 30 minutes less drive time coming back than going down. It was through Ohio, West VA, VA, NC and into SC with a few hundered miles of some hills. Also I did not refill until I started back so there was about 70 miles of town driving on the first tank too and when I got back I did not fill up until just today after about 30 miles of town driving with a couple of cold starts too so actually hiway MPG was likely higher. Not too bad for a 16 year old 4x4 truck with about 172k on it and fairly loaded as well. It runs real good and I always use premium in it too as it will knock on anything less and if I retard the timing (it is set 6 degrees above stock) to use lower grade fuel, MPG and performance greatly suffers. Truck does not use or leak any oil still but the 10 bolt rear end is starting to make a little gear noise now depite frequent servicing (it is really to lite for that truck). I changed oil before I left and it was still full when I got back.