What type of engine oil should be used for Citroen C5?

[LaRuth]

Citroen C5 is suitable for engine oil with the specification of 5W30, but 5W40 can also be used. Both 5W30 and 5W40 have the same low-temperature fluidity, but their high-temperature performance differs. 5W40 offers better high-temperature protection and sealing performance. The viscosity of engine oil changes with temperature, so special attention should be paid to its performance under both 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, ensuring smoother cold starts for the car. The second number represents the kinematic viscosity of the oil at 100°C. A higher value means the oil can maintain its viscosity better under high temperatures, which can also be understood as providing better lubrication performance in high-temperature conditions. The method for changing the engine oil in a Citroen C5 is as follows: Wait for the engine temperature to cool down, 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 for about 30 seconds to allow the oil in the main oil passage to drain; Use a specialized wrench to remove the oil filter; Apply engine oil to the oil seal of the new oil filter and tighten it clockwise by hand; Pour the new engine oil into the oil filler cap on the engine valve cover. Generally, fill up to three-quarters of the oil container; Start the engine and let it run for 5 minutes, then check for any leaks around the oil drain plug and oil filter. If leaks are found, repairs should be made; After stopping the engine, pull out the dipstick to check if the engine oil level is within the standard range.