New to the Club w/ 2005 GXP (oil/ gas)

[BigBonne]

Im new to the club and want to share as much info, and learn as much info as possible. I have not taken any pics of my car yet but I will soon. I bought my car with 84000+ miles on it, and now I'm at 87000+. I am always looking to improve (especially gas mileage) so I would like to know any tips or suggestions.. I read many post before I joined. And I appreciate all the info. I am have a synthetic oil change to day, and using a K&N filter. I want to know how many quarts will I need .
I get bad gas mileage like 14.5 mph. I need to improve this any suggestions? I know to have the fuel filter changed, but I want to know is there a certain type of good fuel filter for the GXP and or any known mechanic cost to change it? AND Yes I love it, and have many of the know issues (shaking at 70 +, moonroof uneven, noise when slow turn (occasionally) oil burning, terrible MPH ETC) I read mostly all post and will take any suggestions.

Im in Wisconsin and preparing for the winter (Battery, oil, air filter, etc) any suggestions on improving MPH etc?

But All in all I love my car BigBonne (Big Bonneville lol) in the Club. I will post pic soon (ima be clean in the snow)

[BigBonne]

Ok i have changed the oil using a K&N oil filter $ $11.04 @ farm and fleet. And it drank 7.5 quarts of oil (Pennzoil pla

Platinum) $5.49 x 8 quarts. It was da most costly oil change i ever did. I wanna know is this oil that great,overrated, or un appreciated? Also do yall/u suggest the K&N air filter n why? What difference does it make? & doed the non ethanol gas (even though it more costly run better (mpg) in the 05 GXP? Also what is the best fuel filter to use and its cost and where to Get it gone in Madison WI? & whats the best way to post to get a response? & Happy Holidays to u n yours ( Christmas & New Year)