BMW 640i xDrive Oil level is low Inspection at your home or office.

Common reasons for this to happen:

• Oil Light Comes On: The Low Oil Engine Warning light will illuminate when the oil level gets lower than it should in the oil pan. This warning light varies on vehicles but in most it looks like an oilcan with a droplet coming out of the spout. If this light illuminates for more than a couple of seconds at start-up the car should be inspected immediately as the oil level is too low in the car. This can lead to damage to critical engine components and expensive repairs.

• Oil Leak: An oil leak can occur in just about any of the oil system components. Common problems are leaking or failing oil pan gaskets. As gaskets and seals age they tend to shrink and fail letting oil escape the system. A leaking gasket can quickly turn into an expensive repair if not addressed, as critical components will not have the lubrication they need to operate safely.

• Worn Piston Rings: Piston rings help control the oil pressure in the vehicle. If they are worn or damaged the oil levels in the car will drop. Look for white or gray exhaust smoke, slow acceleration and excessive oil consumption. This problem can quickly damage critical and expensive engine components such as the pistons themselves and should be repaired quickly.

• Faulty Worn Valve Guides: Valve guides are a cylindrical piece of metal that is pressed or cast into the cylinder head. They help to conduct heat away from the combustion process and into the cylinder head where it may be taken up by the cooling system. If valve guide seals are worn, cracked or broken the engine will suck oil down the guides and dump it into the cylinder, which will pull oil from the lubrication system. Oil levels will drop. This problem should be addressed as soon as possible.

• Incorrect Oil Type: Engines can be filled with low viscosity synthetic oil, which reduces friction and increase fuel efficiency. A lower viscosity oil is thinner and can leak past rings and the seals on valve guides resulting in a loss of oil. Synthetic oil should not be used for the engine break-in period.

• Assembly Mistakes: Piston rings that are not seated or sealed properly can cause oil to leak out of the engine. This problem can result in significant oil loss. The engine must be rebuilt to correct this problem.