Is it necessary to replace the filter when using a circulation machine for oil change?

[BeauLee]

The concept of replacing the filter applies only when changing the engine oil. However, changing the engine oil does not require the use of a circulation machine. Only transmission oil involves the use of a circulation machine for replacement, but transmission oil does not have a filter at all. Additional information: Introduction to car transmission oil replacement is as follows: The replacement cycle for automatic transmission oil is every 2 years or 40,000 kilometers. Due to the highly precise internal structure of automatic transmissions and the high cost of repairs, coupled with the fact that the commonly used gravity oil change method cannot completely replace the oil, it is important not to delay the replacement of automatic transmission oil to avoid greater losses. The location for changing the transmission oil is marked by two bolts on the transmission housing: the upper bolt is the oil filling hole, and the lower bolt is the oil draining hole.

[LeChristian]

20 Years of Car Enthusiast Experience: When Using a Flush Machine to Change Transmission Fluid, You MUST Replace the Filter Simultaneously! I've seen too many people try to save money by only changing the fluid, only to have their transmission fail within three months. The pressure from the flush machine can dislodge metal debris sediment, which will then flow directly into the solenoid valves without a new filter to block it. Japanese cars typically have the filter screen inside the oil pan, while German cars often have external filters. I've personally replaced the filter on an old Accord - when I opened the oil pan, it was completely clogged with sludge. Never trust repair shops that claim the filter is still usable. Those parts cost between 50 to 300 bucks, which is far cheaper than repairing a transmission.

[VanEvangeline]

From a technical perspective: The flush machine uses 12 liters of new oil to clean the transmission, but the average pore size of the filter is 20 microns, and the circulation pressure cannot remove deposits. Experimental data shows that in transmissions without filter replacement, the concentration of metal particles in the new oil returns to pre-change levels within 48 hours. Most manufacturers recommend replacing the filter/filter screen assembly every 60,000 to 80,000 kilometers. Special attention should be paid to CVT transmission filters, which come in two types: paper and metal. Metal filters can be cleaned and reused but require professional equipment. Removing the oil pan to replace the filter also allows for the replacement of the sealing gasket to prevent oil leaks.

[MaggieMarie]

The maintenance manual clearly states: Transmission maintenance includes fluid and filter system renewal. Last year when I was hesitating about doing a flush, the service supervisor showed me the condition of the old filter using an endoscope - the metal mesh was deformed. He did the math: replacing the filter costs an extra 400 yuan, while repairing the transmission would cost at least 8,000. Nowadays, some smart flush machines can detect filter pressure differentials, showing red alerts when values exceed standards. It's advisable to have the shop check the filter model in advance, as some imported car filters may require a week's lead time for ordering. After maintenance, always request the old parts to confirm replacement was actually performed.