A word of caution to DIY oil changers:

If your car is still under warranty and you have a warranty claim, the claim may be disallowed because there is no proof that the maintenance (oil change) was performed as required under the warranty.

A receipt stating date & mileage that Bob from Joe's garage changed the oil is proof; a receipt for oil and a filter that you change yourself does not. The argument is that you may have purchased the oil on a certain date, but there is no evidence of when or if you changed it.

If the warranty claim is for an item disconnected from the parts affected by the oil change (e.g. radio); this of course would not apply.