Thurston Car Talk: Transmission Service Defined


Submitted by Bron at Bron’s Automotive

I sometimes get asked why we do transmission services and what a good transmission service involves.  In 35 years of servicing and repairing transmissions, the reasons and the methods have changed.  Transmissions are much more reliable if properly maintained. The one thing that is constant from the past is that transmission fluid gets oxidized over time and this causes a film of varnish to build up on valves and solenoids, which will eventually make them stick and not function correctly, so the most important thing we are doing is changing the fluid.

In the past the practice was to pull the transmission pan and change the filter, then refill with fresh fluid.  The pan typically holds about 5 quarts of fluid and the rest of the 12 to 15 quarts capacity is in the torque converter and other areas of the transmission, so this older method replaces less than half of the fluid in the transmission.  Most modern transmissions have “cleanable screens” instead of filters, and these do not need to be looked at.  They only get debris in them if something is coming apart in the transmission, which means the transmission is in need of repair. Older transmissions also had adjustable bands that the technician would attend to, but modern transmission now have non-adjustable bands.

Most modern shops today have a transmission flush machine that taps into the transmission cooler line and adds fresh fluid as old fluid comes out.  You can think of it like a blood transfusion.  This method replaces 100% of the fluid with fresh transmission fluid.

The last thing you need to know is that unlike the old days when there were only two types of transmission fluid, there are many more today, each engineered for a specific reason.  Modern transmissions have a variety of clutch materials and many need the same fluid they were engineered for to operate properly and last a long time without problems.  Some shops use chemical additives to make the lowest cost fluid “act” like the more expensive types.  At Bron’s Automotive, we believe it is wiser to use the exact fluid that the transmission was designed to use, with no additives.

We have over twelve types of fluid that we use depending on what your transmission was designed for.  Bron’s Automotive has been servicing and repairing transmissions in Olympia, Tumwater, Lacey, and Thurston County since 2002.

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