Engine oil never goes anywhere or gets used up. Therefore, it is important to check the oil in your BMW regularly, as low levels can signify leaks. If all oil is lost, the damage to a BMW engine will be extensive and costly and may even require a new engine. According to AutohauzAZ, engine oil is dark or honey-coloured and greasy. Signs of leaking oil are a burning smell or the presence of wet spots and/or drips underneath the engine and/or car.
Valve Cover Gasket
Leaks from the valve cover gasket are common in many BMW engines. Valve covers sit at the top of the engine to protect the valves and rocker arms. The covers are bolted to the engine and sealed by a cork or rubber gasket. Leaks or seeps can occur even with a new valve cover, but are more common on older cars. According to RepairPal, valve cover gasket leaks are common after 60,000 miles. Applying sealant can sometimes fix the problem, but it is best to check with a certified mechanic.
Oil Pan Gasket
Many BMW engines feature an oil pan that allows for easier access for engine repairs and overhauls. However, it is common for the gasket on the pan to leak as the BMW ages. Replacement will require removing the car's front suspension.
Rear Main Seal
It is common for the rear main seal on a BMW's engine to leak. According to members of the BMW Car Club of American, rear seals fail when there is too much wear on the crankshaft and the lip is unable to control the output of fluid.
It is common for oil leaks to occur in older BMWs when drivers use synthetic oil in the engine. This is generally due to older seals, which tend to leak with synthetic oil. Pelican Parts recommends that drivers use non-synthetic oil in older BMWs.