Increase Gas Mileage?

you can run a good set of Bosch plugs in it and a good k&n filter with mobil one synthetic oil and it will actually boost the mileage a little on it,that one should get a little better than that any way,we had an old one that had a lot of mileage on it and it got 22 miles to the gallon using the air conditioner,and it was an automatic,so yours should do a little better,check the timing on it ,thats really important on those if the timing chain gets a lot of wear on it they will go through a lot of gas,i think you,ll find that mobil one synthetic oil is actually better than royal purple when it comes to gas mileage,and the bosch plugs will burn the gas a lot better also,but this is a few things that will help it,try to watch the way you pull out in it,and dont do no jack rabbit starts and that should also help a lot,you should be able to ger at least 22 or maybe more from it,especially with the in line 6 thats a good engine,good luck with it hope this helps.