Transmission filter changing
Customers often ask if they should change the filter as well as the fluid.
In the past, automatic transmission fluid was changed by removing the pan, changing the filter and gasket and refilling with 1/3 the capacity of the transmission. This was the only method known to change the fluid so it was the acceptable method.
When transmission flushing equipment was introduced to the market, people started to ask, “what about the filter?” “we used to change it, why don’t we have to change it now?” The answer to this is, it was changed before because we already had the pan off so “we might as well” plus the filter company’s packaged the gaskets with filters and encouraged this practice.
An automatic transmission is a closed hydraulic devise with no foreign matter being introduced. Therefor, if the filter on a transmission should ever become plugged, it is plugged with transmission parts! This means the transmission is past the point of needing a fluid change. An engine on the other hand is constantly exposed to foreign matter (air and fuel) which brings in contaminants as well as the combustion that creates many other byproducts. The engine oil filter is designed to filter these products out.
Many transmission manufacturers use only a screen on the fluid pickup to filter out any casting flaws or debris that could be poured down the dipstick. Some manufacturers do not recommend changing the filter.
The fluid will break down and needs to be changed, the filters do not plug up on a healthy transmission.