Your Corner Wrench: Flushing away your vehicle problems, or your money?

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It doesn’t matter what type of service facility you and your vehicle frequent. Be it a small indie shop, a national franchise centre, or a factory dealership, you’ve probably been asked if you’d like to have any number of fluid flushes and treatments done during a regular service visit.

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It’s become so common that most automakers provide information in their owners’ manuals stating that no chemical flushes are required to maintain the warranty — and that they are not recommended by the manufacturer. Very few customers who got hit with the upsell at the service counter ever had any concern with their transmission fluid, or power steering or brake fluids. Still, these days, there are several changes in auto design and production that throw even more questions at the supposed value of power-flushing.

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Your Corner Wrench: Flushing away your vehicle problems, or your money? Back to video

Does your fuel system actually need purging?

Direct injection is becoming more common each year, with even entry-level compacts using this design. Fuel is injected directly into the combustion chambers, without having to travel through an intake manifold. The benefit is better performance and efficiency, thanks to putting the fuel exactly where it’s needed at precisely the right time.

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But as many early adopters of this technology learned the hard way, the problem is that deposits can build up on the back of the cylinder head valves under load speed, or stop-and-start running. This leads to poor idle and stumbling on acceleration. Curing this through any type of treatment delivery through the injectors – such as additives in the tank, or with injection purge equipment – is a total waste of time.

None of those cleaners and de-carbonizers will ever touch the back of the valves. If your direct-injection engine really has a carbon buildup problem, having the manifold removed and the valves blasted with abrasive material is likely the only cure.

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Flush your transmission?

Oh, for the good old days when there were only two types of automatic transmission fluid, those being Ford’s Type F and GM’s Dexron. Now there are over a dozen different types of fluid commonly used in popular vehicles, and their prices can exceed $40 per litre. Most transmission flush equipment requires double the capacity of the transmission to complete the exchange process, meaning 15 or 20 liters or more, and that’s quite an ouch to the wallet!

In addition, some modern transmissions are labeled “non-serviceable” in terms of fluid and filter replacements. Some of these, such as Ram’s popular eight-speed unit, only have the filter available in combination with the pan, at a cost of more than $200. Doing a transmission flush without replacing any filters is just as much a waste as using those aforementioned fuel additives to clean valve deposits.

Don’t try to save some money by opting for a “universal” fluid, rather than a proprietary one. That can lead to internal problems, and your manufacturer’s warranty can be denied. You can always opt for a regular flush, using a simple external pump. This will have the desired effect of exchanging as much fluid as possible without breaking the bank by purchasing cases of fluid. Just dropping the pan, and draining and refilling the fluid, will usually only remove about half of the total capacity. It’s fine to try to save a few bucks, but if you don’t do it right, it could ultimately cost you even more.