Depending on where you bought the bike would be your first best indicator of what the bike needs. If you purchased it from a dept store or sporting goods store then it probably needs alot. If you purchased it from a bike specific shop then it should NOT need anything, as the on site mechanic should have seen to the bikes needs before it left the store. Your brakes could be rubbing and slowing it down and yes low tire pressure could also be a cause or it could just be a "bad" bike?....Take it back where you bought it especially if from a bike specific shop and tell them to do it right and if a dept store, just take it back, they wont have a clue. There is a reason that specific lubes and degreasers are made for bicycles, use only these to get the most life out of any bike.
