Auto 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.

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**

Flush vs Fluid Change

Old fluid vs new fluid

Transmission Fluid Change

In a fluid change, also known as a transmission service, the pan is drained and the filter is replaced. Not all of the fluid is removed as the bulk of it can remain in the torque converter and cooler plus lines, sometimes more than.

Although it doesn't remove all the fluid in the system a fluid change with a new filter is still better than no service. So even though the fluid won't be all new but diluted with new, it will still be more effective than just 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 ineffective fluid will have a shorter lifespan and could potentially lead to failure. A transmission fluid change is recommended every 50 000km or every 2 years, which every comes first.

Transmission Flush

Many people argue that a transmission flush is 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 most prefer a transmission flush, where all of the old fluid is removed throughout the full system and brand new fluid is added allowing optimal performance as the transmission only runs on new fluid.

Here at Euro King Auto Engineering, we first drain the fluid, add a flush chemical and top it up, this is then run through the system and allowed to stand for half an hour so that the chemical can break down any grime that may be stuck in the torque converter, cooler, lines etc, this is then drained, the pan and filter removed and our custom modified flush machine is connected to the transmission still with the pan removed the fresh fluid is pumped through the system, this way we know all the flush chemical and old fluid are removed. Although a longer and more messy process we know we have a better chance of providing a better job.

A transmission flush is a perfectly safe service for you car and is worth the extra money it costs. Transmission flushes have a bad rap as some people expect a flush to fix a major problems, such as slipping and stalling. There are those people that only believe in getting the transmission flush once the problems arise and generally don't bother about transmission maintenance at all, or say their service book says the transmission is sealed and filled for life, trouble is there is nothing to say how long is life or if you do have the transmission serviced it life will be extended.

There are many people that will often tell stories about how their transmission failed right after a flush. The reason why transmissions can fail soon 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 a major problem, it is a regular service just like a oil change in your engine, so don't expect any miracles to happen for a dying transmission. A transmission flush is recommended every 75 000km or 3 years, to be performed in place of a fluid change or to replace fluid change altogether.

View with pan removed showing solenoids & valve body

When Not to Get a Transmission Flush

A transmission flush isn’t some magical, cure-all service that can solve any problem. If your transmission has serious internal problems or is already failing, a transmission flush can’t save it now. A transmission flush is meant to be part of routine maintenance and not something you get when you start experiencing problems.

If it’s already failing, our best suggestion is a rebuild, because getting a transmission flush now might cause it to fail even sooner. The reason most transmission flushes fail is because the owners bring in their cars too late, when problems have grown too big. And as soon as the transmission fails, the owner rushes to the conclusion that it’s the fault of the transmission flush and not the failing transmission itself.

If you want to try to salvage your car then by all means get a transmission flush, but don’t count on it to perform any miracles. A transmission flush is not supposed to be a solution, and the bad things you hear about them are often from owners who don’t take care of their cars until problems occur. Ask an owner that gets a flush on a routine basis compared to an owner who doesn’t get one until problems come up, you’ll see that you get answers on both ends of the spectrum.