AIP Use Ratings The American Petroleum Institute (AIP) has established a method for classifying lubricant performance with different types of engines and different types of use. Each performance rating was verified by engine experiments. Sulfuric acid ash and total base sulfate ash are lubricant properties measured by laboratory tests (ASTM-D874) used to determine the potential for formation of metal ash. The residual ash is related to the composition of the engine oil additive, and it is important to predict that the lubricant may cause valve damage under certain conditions. Sulfuric acid ash is related to the total base value. The BTN is also a laboratory test value (AsTM D 28% or 4738), which measures the alkalinity of the engine oil and its ability to neutralize acids. When TBN increases, sulfate ash increases, lubricant BTN exceeds 10, and sulfate ash may exceed 1.0%. The total base number is important for controlling the deposition of a four-stroke engine and its effect on all diesel engines and high-sulfur fuels.
During the oil change cycle, the oil deteriorates due to combustion products and engine pollution. Some components in the lubricant and additives slowly decrease until they are used up. Therefore, irrespective of the formula of the oil, the oil must be regularly drained. The length of the oil change cycle varies with the operation of the engine, the quality of the fuel, and the quality of the lubricant. In general, shortening the oil replacement period can extend the life of the engine by quickly replenishing the protection quality in the lubricant. When replacing the oil, be sure to install a new engine oil filter. Do not replace the imported filter with a simple copper mesh, otherwise it will cause great damage to the engine.