This is a very important question.  The oil within the engine is a very vital part of the engines mechanical process.  The oil helps to lubricate all of the motors parts and make them run in a smoother fashion.  Without oil the engine would not run.  If the oil was gone from the engine and the motor was on and working there will be serious problems that may occur.  So to answer the question, the oil in a motor should be changed every three thousand miles.  Doing this regular change shall keep the motor working smoothly and efficiently.

     The spark plugs within your engine should be replaced every 35,000 miles.  This is different if the spark plugs are made out of platinum, if so they should be replaced every 65,000 miles.  You should also make sure to inspect the spark plug wires for any damage and replace them, only if necessary.  To change the wires less you should buy higher quality products.