Okay then. Refilled with Texaco 87 octane, used Neutra 1 bottle for 27 gallons. I am still sitting on full after 72 miles of driving with the A/C on, extended idle time etc.
It had to be the Shell high octane gas. I don't know how or why. My wife reports the same from the 87 octane Phillips she has been getting. I did not Neutra dose her. I wanted to see how one did with, one without. Both of our mileages have gone back pretty much to normal. Only difference being, not using Shell high octane gas.
Sorry Bob and anyone else that thought I was condeming Neutra as the cause. Now, I would very much appreciate an educated/semi-educated guess as to which was the cause. Was it the brand of gas (Shell) or the high octane used in low compression motors? Thanks for all of the feedback. Bob, this forum is worth a donation to me. On it's way.