When Should You Change the Transmission Fluid on a Toyota Siena?by Dan Ferrell
Just as you regularly check and replace the oil in the engine, you should inspect and change the transmission oil in your Toyota Sienna at regular intervals. Toyota recommends replacing the transmission fluid every 15,000 miles or 12 months. But there are some other facts you should take into account that might shorten this interval.
Toyota recommends inspecting and changing the transmission oil sooner if your driving habits fall under one or more of these conditions: Towing a trailer regularly; making constant short trips of less than five miles under freezing temperatures; idling excessively or frequently driving at low speeds; driving on rough, muddy, unpaved or slat-covered roads.
Check the transmission oil with the engine under operating temperature and idling. Set the transmission in park and pull the transmission oil dipstick. The oil should read between the add and full marks, and have a reddish and transparent color. If the oil shows a brownish and opaque color, replace it.
Just like engine oil, the fluid in your Sienna transmission might become contaminated with friction material, moisture and dirt over time. If not changed at the recommended intervals, contaminated oil will cause excessive wear and damage of internal components.
The oil recommended by your car manufacturer for your Toyota Sienna combines several additives to function properly with the friction clutches and bands inside the transmission.
As it travels through the torque converter and the transmission body, the oil absorbs great amounts of heat, which the oil cooling system must remove to avoid transmission failure.
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