According to the U.S. Bureau of Public Roads, 63 percent of motor vehicle trips equal six or fewer miles. The American Petroleum Institute, however, has indicated that engines require as much as six miles of travel to reach normal operating temperatures, and their oil may take even longer. Frequent short trips often allow water, fuel and acids to accumulate in the motor oil and sludge and varnish to form in the engine. Using AMSOIL synthetic motor oils and AMSOIL By-Pass Oil Filters help protect engines from the rigors of short trip driving.
Water: Water is a normal combustion by-product that by-passes the piston rings in its gaseous state (steam), then condenses on internal engine walls when the motor oil is not warm enough to drive it off as steam. Circulating oil picks up the water and carries it to the oil filter. Conventional paper filters cannot trap water, so it continues to circulate with the oil, where it depletes additives and reduces the oil's ability to lubricate. When the engine is shut down, the water may accumulate on engine metals, promoting rust. The AMSOIL By-Pass Oil Filter traps water.
Fuel: Fuel accumulates in the oil during repeated short trip driving because the engine runs with a closed choke when it's cold. The closed choke allows lots of fuel into the combustion chamber, more than is burned. The excess by-passes the rings and gets into the crankcase. The only solution for fuel in the oil is long-trip driving. Warming the engine to normal operating temperatures promotes its evaporation.
Acids: Some fuel by-products interact with water to form acids. The water must be in its liquid form, so this process takes place more readily in the cool short-trip engine than in the warm long-trip engine. AMSOIL synthetic motor oils are high TBN (Total Base Number) oils, which means they are made to neutralize acids. Most passenger car motor oils are formulated with significantly less TBN than are AMSOIL synthetic motor oils.
Sludge and Varnish: Sludge, a soft sticky material that accumulates on surfaces, and varnish, a hard material that adheres to surfaces, form as water, acids and other oil contaminants interact in the oxidizing engine environment. Since short trip driving encourages water contamination of the engine oil, vehicles frequently engaged in short trip driving are prone to developing sludge and varnish. Because AMSOIL synthetic motor oils are highly resistant to oxidation and contain powerful acid fighting TBN chemistries, they help prevent the formation of sludge and varnish.
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