Hi guys: I have 2003 chevy silverado half ton engine size 305 pickup truck. I bought this truck when it has 74000 miles on it. Now it has 120k miles on it. Since i bought it from the dealer i never go for the tuneup accept i change the brake pads. Can any one please advise me does it needs to go for the tuneup or any thing if it needs to be change. I dont feel any difference the time since i bought it it still running smooth.