Essential Guide to Changing Car Fluids by Sam Freij

Sam Freij is the Kingdom Maintenance Director at Alissa Holdings. He has over 23 years of automotive experience under his belt. He will be sharing his thoughts with us on numerous automotive topics every week. He looks forward to answering your questions.

Dear Readers,

This week I would like to bring up a very important maintenance topic focusing on the importance of exchanging fluids in your car (especially your transmission fluid). But first...

A Little Bit of History

Manufacturers have always had a suggested service interval for changing fluids, including transmission fluid, whether it is an automatic or manual shift. When automatic transmissions were first introduced, the suggested service interval was about every three years or 50,000 km. The transmission service consisted of draining the fluid from the pan and maybe the torque converter and replacing the filter (most common design in GM & Ford models). This was a realistic time frame interval and service method as the vehicles were very open and did not build up much heat.

Around 1980, US auto manufacturers downsized cars for fuel economy and mounted the powertrain transversely into the area previously reserved for the engine only. As you can imagine, this increased the heat retention in the engine, especially for the transmission. The demands placed on the transmission fluid have increased exponentially as a result. The unexpected warranty costs from this required a switch to synthetic fluids that can handle the heat better. Even synthetic fluids and their additive packages fail over time, as evidenced by the number of valve body failures caused by gum and varnish deposits inside the transmission case. The image below displays the main areas in a transmission:

General Motors tried an experiment of sealing the transmission, stating that “it was good for lifetime service”; however, that failed miserably! What happened was that the fluid and additive package failed to keep gum and varnish off critical components like the valve body and clutch packs. These deposits stick to the valves in the valve body and on the clutch assemblies, causing them to move sluggishly or become completely stuck, resulting in improper operation or a burned-up transmission. Clutch packs can slip, hang, or grab, leading to severe shifting problems, which can appear in any transmission, some with really low mileage.

Most car manufacturers realized that a transmission fluid exchange was needed, so they engineered a transmission flush machine for their vehicles, making it an essential piece of equipment for their dealer network (meaning dealers are required to own it). Most transmission fluid exchange machines use a bladder-type system to hold the new fluid (usually about 16 quarts). The old fluid flowing from the pump to the transmission cooler is interrupted, and the equipment is inserted into the loop. The old fluid supplies the hydraulic force to exchange the old fluid for the new, sometimes supplemented with a low-pressure pump. The new fluid is returned to the pan, flowing through the filter first, then into the pump, valve body, etc.

The response from aftermarket equipment manufacturers to car manufacturers' equipment has been excellent, with tools like the bulky T Tech II and others from Wynns, BG, and Mighty made by White Industries.

My Recommendations on Changing Car Fluids

1. Do a transmission fluid flush service every 30,000 km

   Most car manufacturers suggest a 100,000 km mileage for transmission service. However, it's better to be safe than sorry; thus, it is advisable to perform a transmission flush service every 3 years or 50,000 km. This could save you a tremendous amount of money and headaches in the long run. If a valve body fails due to excessive gum and varnish deposits, the expected cost can easily reach $5000 for a transmission replacement.

2. Use only full synthetic fluids for your transmission fluid service

   Most older Asian vehicles experience shifting problems after a transmission fluid exchange when other fluid types are used. Always check your owner's manual or contact your local dealer.

3. Service the power steering fluids every 30,000 km

   Power steering fluid is critical for the functionality of your steering system. It lubricates the power steering pump and cools your steering gear, which steers the front end of your vehicle. Over time and with heat, viscosity decreases, and the oil base fluid becomes thin, leading to cracks in seals and grommets, causing expensive leaks.

4. Radiator coolant fluid can nowadays go up to 100,000 km without issues, thanks to new technologies

   Having said that, I recommend that you always check your fluids during every oil change to ensure they are up to standard. You can also request a free temperature tolerance test at most workshops or your local dealership.

5. Flush your brake fluid every 30,000 km

   The industry tends to lag here, recommending servicing brake fluid every 60k or based on condition. Contaminated brake fluid is usually very dark and grimy looking. It may also cause a spongy brake pedal, but not always. If you suspect your brake fluid is contaminated, you should definitely have it changed. If there is more than 3% water in your brake fluid, it can superheat, causing your brake lines to explode or leak under pressure, which is dangerous and expensive to repair. Brake fluid is very hygroscopic and readily absorbs water when exposed to air.

I hope this information is useful and that our little window here at YallaMotor will help you better maintain your vehicle and protect your investment. Send in your questions to [email protected].

Wish you all a great weekend. Drive Safe.

Sam Freij