For a go kart what brake system would be better?
Emissions related - yes. O2 sensor - sounds like he's guessing. Something is wrong but as long as the car behaves normally and the fuel economy is not suddenly very bad it can be driven normally without harm. Honestly, the O2 sensor (particularly the forward one, which controls mixture, more than the rear one, which just monitors the catalytic converter) is probably overdue for replacement anyway. They are good for 100K miles or so and work more or less for another 100-200K miles but fuel economy tends to suffer. Replacement is $200-$300 (see source and use your own zip code). The first step to avoid throwing money at the problem is to find out what the codes are. Most chain auto parts stores (Autozone, Shuck's/Kragen/Checker, NAPA) will read the codes and attempt to reset them for free. If the code is an evap code, usually P0440 or P0442, the most likely cause is a loose or leaky gas cap. Aftermarket gas caps do not have a good reputation - go to Toyota for that.
Lets put it this way. You do not need to clean your house. You can live in there for 20 years and never use a vacuum cleaner. But should you? For longest health(eg best performance) change the oil when it says so. Sure you can go until it becomes tar-like again, but then it won't work and changing oil will be living nightmare. Your check engine light is for a number of reasons- enngine oil to low coolant to a $500. cheque on the air cleaner addressed to you. Maybe you should pop the hood and take a look?
Sorry wrong section. Find a web site with go carts.
Yes not changing your oil can make your check engine light come on. The sticker on your windshield can only estimate by time when you need to change your oil, you should change your oil by your mileage. Keep track of your odometer reading to tell if you've driven more than three thousand miles between oil changes.
