Transmission repair is a major, time consuming, and often expensive automotive repair. That is why it is so important to keep your transmission properly maintained. We can repair or replace the transmission for you, but the most important thing we can do is regularly change your transmission fluid. This is important because over time, as your transmission wears, bits of metal from the gears will contaminate the fluid. In addition, the extreme heat generated by an automatic transmission will cause the fluid to break down. Low fluid levels can seriously damage your vehicles transmission. Unfortunately most German cars (now some Asian and American cars) no longer have a dipstick to check fluid level.  Most of them require the vehicle transmission fluid to be about 85 degrees to check the level. I guess they don't know how hot it gets in Arizona. To add insult to injury most German vehicle manufacturers state the fluid is good for the life of the vehicle. I believe that could be translated as until the warranty is up. A good rule of thumb is to replace the fluid every couple of years with the original fluid. Very often I get a complaint my transmission services are to expensive and the so and so chain store does them for $100. Next thing I know they are back complaining about how their car shifts. If they are lucky I can flush out the generic transmission fluid with genuine at the cost of approximately $25 per liter using 15-25 liters and the transmission starts shifting correctly. There are at least ten different transmission fluids for German vehicles.