The motor oil gets contaminated and loose additives with time.To ensure better engine protection,you have to change engine oil and filter after every 3 months or 3000 miles of driving generally (whatever comes first).
Ten Step tutorial to change engine oil
Change engine oil as per the guidelines given by your car manufacturer.They provide the timeline for oil change.
Make sure that the engine is warm.The best time is when returning from a drive.Please turn off your engine before changing oil.
Raise your car using jack .
Place a pan below the oil pan drain.
Remove the drain plug using wrench.
Make sure that oil is drained completely.
Check gasket for cracks surrounding the drain plug.If cracks are there,you need an oil filter.Buy a new oil filter and coat it with engine oil.
After that reinstall the drain plug.Make sure its tight and no leakage is happening.Fix the oil filter also.
Fill the engine as per provided guidelines.Do not ovefill
Restart the engine and Check for any leaks.
Important Points
Transfer the used engine oil to a container.Mark it as "used engine oil".Give it to your service station guy
Always buy engine oil which meets your car manufacturer's warranties.
Avoid direct contact with heated areas under the car While changine oil
Go for multi grade oil if weather conditions fluctuate in your location