Bmw 3 Series SERVICE MANUAL (Bentley, Publishers Cambridge, Massachusetts)

Power Steering Fluid
The power steering fluid is Dexron III® ATF, or equivalent. The system is permanently filled and does not have a drain. Routinely adding ATF is not required unless the system is leaking.

Brake Fluid
Brake fluid absorbs moisture easily, and moisture in the fluid affects brake performance and reliability. This is why brake fluid should be flushed from the system every two years. When replacing or adding brake fluid, use only new fluid from previously unopened containers. Do not use brake fluid that has been bled from the system, even if it is brand new. Use only DOT4 brake fluid. See 340 Brakes for more information.

Spark plugs, replacing
To accessthe spark plugs on 4-cylinder engines, remove the cover from atop the spark plugs. Using the special spark plug wire removal tool (attached to rear of cylinder head beneath engine cover), gently pull the spark plug wire from the spark plug. Blow away any dirt from around the base of the plug to prevent it from entering the engine. Remove and install the spark plugs one at atime.

Idie Speed
Engine idle speed can change due to a number of factors, including normal wear. The idle speed is electronically adaptive and non-adjustable. See 130 Fuel Injection for more information.

Battery
Battery cables should be tight. The terminals, the cable clamps, and the battery case should be free of the white deposits that indicate corrosion and acid salts. Even a thin layer of dust containing conductive acid salts can cause battery discharge. To remove battery corrosion, begin by disconnecting the cables. Disconnect the negative (-) cable first. Clean the terminal posts and the cable clamps with a wire brush. Clean the main chassis ground terminal next to the battery. Corrosion can be washed away with a baking soda and water solution that will neutralize the acid. Apply the solution carefully, though, since it will also neutralize the acid inside the battery. Reconnect the cable
clamps, positive (+) cable first. Lightly coat the outside of the terminals, hold down screws, and clamps with petroleum jelly, grease, or a commercial batteryterminal corrosion inhibitor.
Batteries are rated by ampere hours (Ah), the number of hours a specific current draín can be sustained before complete discharge, or by cold cranking amps (CCA), the number of amps available to crank the engine in cold weather conditions. In general, replacement batteries should always be rated equal or higher than the original battery.

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