There are two types of garage door openers The alkaline type and the deep cycle batteries. These can be purchased at many stores and are easy to replace. To change your batteries, you will need to bring them to your local garage or DIY center , and be examined by a trained mechanic, because they are more complicated than the other kinds of batteries. The same applies to changing your car's engine oil. If you're not sure what type of oil you are using it is advisable to ask a mechanic at your local garage where you purchased your car to assist you in this regard.