It's important to check your oil level regularly, particularly before long drives. This will keep your car running smoothly. Beginning in 2006, 3-series BMWs abandoned the standard oil-check method--the simple dipstick--in favour of a less reliable computer sensor. If you have a 3-series, this is probably what you have, but if you're unsure, it's easy to check.
Start your car and check your dashboard readouts. If an oil can light appears between the speedometer and the tachometer, you have an electronic oil sensor and no dipstick. There will be no readout at first, but let the car run for a few minutes and it should appear. The left notch is the minimum safe oil level; the right notch is maximum. If the oil level is very close to the left notch, you should add oil.
Park the car on a level surface if you do not have an electronic oil readout. Let the engine run for a few minutes, turn it off, then wait about five minutes before opening the bonnet.
Find the dipstick. On 2007 BMWs, this will be located to the upper right of the engine, and have a small circular handle protruding upwards.
Pull out the dipstick and wipe it clean with a paper towel or other lint-free cloth.
Reinsert the dipstick all the way into its tube, then remove it again.
Examine how far the oil has risen on the dipstick. The dipstick has two notches on it--the lower one represents the minimum safe oil level; the upper one represents the maximum. Never drive the car below the minimum level, and never fill it to over the maximum. Avoid this by only adding oil when the level is just above the minimum.
Find the oil cap. This will be on top of the engine, next to the "BMW" inscription.
Remove the oil cap and, using a funnel, pour in BMW High Performance Synthetic Oil.
Replace the cap and close the bonnet.
Some have called the new BMW electronic oil checker inaccurate, and maintain that the only way to be sure of oil level safety is to change the oil entirely, either by yourself or with the help of a dealership. Talk to local BMW dealers or experts about this issue.