Hello,
Just need some help with some general maintenance for my 2003 Xterra.
1. Can anyone recommend a good Fuel Injector Cleaner or are they all the same? (Also any other cleaners to improve my X)
2. I was considering buying a K&N air filter, will it help anymore then a noraml air filter?
3. What kind of Anti-Freeze (brand, type) should I keep in hand to replace, replenish what I have now. I noticed that the current Anti-Freeze is dark green.
4. My best friend is a manager at a Valvoline Instant Oil change place and I am due for a oil change and was thinking about going with full synthetic. Does the oil brand really matter? I don't mind changing it myself, just a pain!

Keep in mind I'm asking these questions to take care of my X, prolong the life of it and to gain the best possible gas mileage! Thanks for all your help.