Transmission Flush vs Fluid Change

What’s the difference between a transmission flush vs fluid change you ask? And which is the more effective service? Before we explain what the differences are, you should remember that the transmission holds fluid within the transmission pan as well as the torque converter. A good majority is actually inside the torque converter, up to 40% of the total volume. With that said, we will go ahead and explain the differences between a transmission flush vs fluid change. 

Transmission Flush vs Fluid Change

As you can tell by their names, a transmission flush and a fluid change are two completely different services. While a transmission fluid change focuses on draining the dirty fluid from the pan, a transmission flush gets rids of all the fluid in the pan, the cooler lines, as well as the torque converter. While it depends how often you should have your transmission serviced, it also matters which service you choose.

**Whichever service you choose, make sure that the transmission filter is replaced, the fluid recommended by the manufacturer is used, and the pan is dropped and inspected for any problems**

Transmission Fluid Change

In a fluid change, also widely known as a transmission service, the pan is drained and the filter is replaced. Not all of the fluid is removed however as a good chunk of it (up to half) can remain in the torque converter and cooler lines. Although it doesn’t remove ALL the fluid, a fluid change is still an effective service at replacing some of the old fluid.  So even though the fluid won’t be brand new, it will still be more effective than the old fluid. Contaminated fluid is the bane of transmissions, as it causes it to overheat as well as work harder. In the long run, a transmission that runs on ineffective fluid will have a shorter lifespan and could potentially lead to failure.

Because of the nature of a fluid change (in that it only removes some of the old fluid), mechanics will often drain and replace the fluid multiple times in order to dilute the fluid to a satisfactory condition. The good news is that you can learn how to do it yourself, which isn’t difficult and will save you a bunch of money in the long run. A transmission fluid change is recommended every 30,000 miles or 2 years, whichever comes first. You can learn more about the cost of a transmission fluid change here.

Transmission Flush

Many people argue that a transmission flush is much more effective than a fluid change. The logic for this is that some of the old fluid can still remain in the transmission after a fluid change, which will only contaminate the new fluid that is added, thereby diminishing its performance. That’s why there are those that prefer transmission flushes, where ALL of the old fluid is removed via a cooler line flush machine or a pump inlet flush machine and brand new fluid is added. This allows for optimal performance as the transmission only runs on new fluid.

A transmission flush is a perfectly safe service for your car, and is worth the extra money it costs. Transmission flushes have a bad rap however as some people expect a flush to fix major problems, such as slipping and stalling. There are those people that only believe in getting a transmission flush once problems arise, and generally do not care about transmission maintenance at all. These are the people who will often tell you stories about how their transmission failed right after a flush. The reason why transmissions fail right after a flush is not because of the flush itself, but because the transmission was not well maintained and already on the verge of failure. A transmission flush is NOT meant to fix major problems, it is a regular service just like a fluid change, so don’t expect any miracles to happen for a dying transmission. A transmission flush is recommended every 45,000 miles or 3 years, to be performed in place of a fluid change OR to replace fluid changes altogether. You can find out more about the cost of a transmission flush here.

TL;DR Version

transmission flush vs fluid change - transmission repair guy