BMW 640i Engine oil is black and gritty Inspection at your home or office.

Common reasons for this to happen:

• 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. Modern detergent engine oils which have detergent additives are designed to disperse the tiny particles or engine sludge and hold them in suspension in the oil so they do not build up on engine parts.

This will make the oil darker in color, and slightly gritty but it’s better for the build up to be trapped in the oil then building up on the vehicles engine parts. Oil can only hold so much sludge and eventually it will need to be replaced.

• Dirty Oil Filter: An oil filter’s primary function is to filter out contaminants in the oil that it picks up while cycling through the engine. Over time an oil filter will become full and will need to be replaced. If it is unable to filter the oil the contaminants will remain in the oil and possibly damage the engine.

• Overdue for an Oil Change: Oil needs to be changed on a regular basis. While oil turning black and getting slightly gritty is normal, extremely black oil that develops globs on the dipstick needs to be changed immediately. The interval between oil changes will vary depending on the type of oil being used but it is a good idea to follow the manufacturers recommendations.

While 3,000 miles used to be the recommendation, most modern oils, especially synthetics can go between 7,000-10,000 before an oil change is needed.

• 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.

• Oil Level is Dropping: If the vehicle is consistently low on oil or the level is dropping sharply over a short period of time, there is probably an oil leak somewhere in the system. An oil leak can lead to a dangerously low amount of oil in the car and should be repaired immediately.