Car engines need oil to operate smoothly and efficiently. Engine oil helps lubricate the dozens of moving and interacting parts; helps prevent rust and corrosion as well as aiding in removing the heat that an engine generates. Modern oil also helps keep an engine clean by removing sludge and build-up. An engine without oil simply will not function.
Brand new engine oil is a lovely amber color but over time it will turn black and in some cases will get gritty. Fortunately, this is usually not a problem; it is simply a result of the oil doing the job it was designed to do.
Need for Engine oil replacement:
Normal Wear and Tear: Regardless of how often oil is changed, eventually it becomes black and slightly gritty. This simply means it is doing its job.
Overdue for an Oil Change: Oil needs to be changed on a regular basis. The interval between oil changes will vary depending on the type of oil being used but it is a good idea to follow the manufacturer’s recommendations.
Oil Light Comes On: In most vehicles, if the Oil Warning light comes on, it is reason for immediate concern. In most cases this will indicate a low oil pressure situation, which could be the result of a failing oil pump or a leak. This can do severe damage to the engine. The vehicle should be inspected and repaired immediately.