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Dealer service best for continuously variable transmissions


- 123RF
- 123RF

The continuously variable transmission (CVT) has been around for many years and, today, it’s becoming more common as automakers work to deliver the increased fuel economy that shoppers demand.

If you drive a vehicle with a CVT transmission, be sure to carefully read and understand its maintenance and fluid-change requirements — and bear in mind that a dealership is the best place to have this type of transmission serviced when the time comes.

Additionally, if you’re buying a used vehicle with a CVT, you’re likely best to ensure the transmission has only ever been serviced by that vehicle’s dealership, for maximum peace of mind and minimized likelihood of expensive repair bills.

Lori Boerio, a service advisor, recently shared a story that helps illustrate why.

A few years back, a customer bought a crossover from the dealership where Boerio works. More recently, that customer’s crossover came due for a transmission fluid change.

“The vehicle needed a service appointment, which included a change of the fluid in the CVT transmission” Boerio says. “The customer called us for a quote, but decided to get a second opinion since she wasn’t happy with our price.”

After discussing Boerio’s estimate and the servicing requirements with her husband (a heavy equipment mechanic), this couple decided to fore go the dealer visit and perform the transmission fluid change at home, in the garage, to save money.

“We ended up learning all of this later on, when the customer found themselves back at our dealership because of transmission problems,” Boreio said.

The customer’s CVT transmission, which was still within its factory powertrain warranty period, began acting strangely not long after the at-home fluid change. Things got worse, and the customer reported symptoms which included slipping, surging, excessive revving, and even performance that was, at times, so sluggish it posed a safety concern.

“At times, they’d even press the accelerator, and have to wait two or three seconds before the vehicle got moving at all,” Boerio says. “Something was seriously wrong with the transmission.”

Boerio’s staff began inspecting the vehicle while the customer waited in the lounge. A few moments later, Boerio and a technician arrived with a small plastic cup filled with a thick and syrupy red fluid.

“This was going to be expensive, so we wanted to explain exactly what was causing the problems,” Boerio said.

The plastic cup was filled with generic Automatic Transmission Fluid (ATF), which the customer’s husband had used to refill the transmission during the at-home transmission fluid change a few weeks prior.

Problem is, in this application (and others) ATF is not compatible for use with the CVT transmission. Most CVT transmissions require filling with a very specific type of specialized fluid designed exclusively for the application. Not aware of this, the customer’s husband had simply filled the transmission with the next closest thing he could find.

Not all transmission fluid is created equal, though, and use of ATF in a CVT transmission can cause a multitude of problems. Transmission-specific fluids often contain special additives designed to support the specific operational parameters of the transmission in question. Further, transmission-specific fluids (like CVT fluid) are typically coloured to help dealer technicians quickly identify problems caused by the use of incompatible fluids.

Use the wrong fluid in the wrong transmission and you might compromise the lubrication performance, compromise internal seals and gaskets and cause strain and damage to various pumps and other components. Use of the incorrect fluid within the transmission can also cause excessive foaming or frothing of the fluid, which effectively changes the fluid’s viscosity and the operational pressure within the transmission. This can rapidly wear out various parts, or even destroy delicate internal seals, which was a likely part of the customer’s problem.

“We showed the customer the red transmission fluid in the cup and explained that when we draw fluid from our CVT transmissions, we need to see a green colour, not red,” Boerio said. “I explained that the fluid used to fill the transmission was the cause of the damage, and that the transmission was destroyed and needed to be replaced. I also explained that no warranty covers damage like this, since the damage was caused by the use of non-factory fluids.”

A proper fluid flush and fill on this particular type of transmission also requires specialized equipment, which was not available to the customer’s husband in their home garage. Without access to this equipment, this endeavour was set up for failure from the get-go.

“This isn’t the sort of thing where you can just drain the fluid and then top it back up,” Boerio explains. “Our technicians use special equipment and computer monitoring to perform this fluid change. It’s not a DIY job you can tackle at home.”

Ultimately, this customer saved a few hundred dollars on a transmission fluid change, but earned a several thousand dollar replacement bill for a new transmission.

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