Changan CS55 uses engine oil with the specification: SL grade 5W-30 mineral oil. If you want to change the oil during later maintenance, Shell HX7 5w-40 synthetic oil is a better choice. The viscosity of engine oil changes with temperature, so special attention should be paid to its performance under low and high temperatures. For example, in 5W-30, the first number indicates low-temperature fluidity. 5W means it can withstand temperatures as low as -30°C. The smaller this number, the better the low-temperature fluidity, making cold starts smoother. The latter number represents the kinematic viscosity of the oil at 100°C. The higher the number, the better the oil maintains its viscosity under high temperatures, which can also be understood as better lubrication performance under high-temperature conditions. The method for changing the oil in a Changan CS55 is as follows: Wait for the engine temperature to drop, allowing the oil to flow back into the oil pan; use a wrench to loosen the oil drain plug and place an oil pan underneath to catch the old oil until it stops flowing; start the engine and let it run for 30 seconds to allow the oil in the main oil passage to drain out; use a special wrench to remove the oil filter; apply oil to the seal of the new oil filter and tighten it clockwise by hand; add new oil through the oil filler cap on the engine valve cover, typically filling up to three-quarters of the oil container; start the engine and let it run for 5 minutes, checking for any leaks around the oil drain plug and oil filter, and repair if necessary; after stopping the engine, pull out the dipstick to ensure the oil level is within the standard range.
