Several parameters are used to decide when it is time to define oil as 'worn out' A more extended interval between changes than for instance the traditional 3000 mile is often allowed however frequent changes are favoured as they are said to increase periods between engine overhaul. If not deciding to replace the oil every 3000 miles and depending just on the oil life indication, do not go above 1 year or 7500 miles for an oil change irrespective of the indication reading. Another strong sort of maintenance done regularly is oil change, as over time, oil gets thin and begins to coagulate, thus causing wear on the engines. Preparations should be made of having some tools such as knife, scissors ready before starting the work and have rags or newspapers in case of spilling some fluids such as coffee or juices. Lift the car well on jack stands, get to the oil drain plug and filter, and put heat to the engine to get the oil to flow. Be careful of hot parts and then take out the oil filler cap, the engine splash shield and the drain plug. Check the old oil for metal fines, clean the threads of the drain plug, and replace it. For V6 engines, unlock the oil filler cap, and unscrew the engine cover, replace the filter together with the O-ring and put new O-ring on the filter, apply some new clean oil on it. For V8 engines drain the level pan using the drain pan, remove the filter , clean the surface and fit the new filter together with a lubricated gasket. When all tools and materials have been taken, lower the vehicle and pour in fresh oil through the filler cap and check on the dipstick. Switch on the engine, look for any sign of leaks and on checking the oil level, add in as much as is needed. Old oil should also not be dumped on the ground, or in a drain. Even if the monitor does not recommend a change the oil and filter should be changed at least once a year and the monitor reset. To reset, start the car and turn the radio to on, press the setup button, hold the Set/Clear button for five seconds and turn the ignition off. Or, insert the key into the ignition and turn it to ON/RUN, depressed the accelerator three times within a five seconds, remove the key and restart the vehicle.