Simple Steps for Checking Transmission Fluid

Transmission fluid not only lubricates the gears and bearings inside the transmission to reduce wear and abrasion, but also performs multiple functions such as cooling, cleaning and transferring hydraulic pressure.

Over time, transmission fluid will gradually age, its performance will also decline accordingly, as the color becomes darker, contains impurities, and may even produce odor. If it is not replaced or supplemented in time, it may lead to serious problems such as improper gearbox shift, abnormal sound, overheating and even damage. Therefore, regular inspection of transmission fluid is an important part of maintaining the health of the transmission and extending the service life of the vehicle.

In general, the vehicle manual will clearly mark the transmission fluid replacement cycle, which is commonly every 40,000 kilometers or 60,000 kilometers. However, in addition to regular replacement as appended by the manufacturer, it is also recommended that you check the transmission fluid in advance when the following cases happen:

Importance of Checking Transmission Fluid

Transmission fluid is the key lubrication medium for the normal operation of the gearbox, responsible for lubrication, cooling, cleaning and transmission of power. Regular checking of transmission fluid is essential to extend service life, improve driving experience and avoid high maintenance costs.

The importance of checking transmission fluid can be simply defined in four aspects.

Reduces Friction and Wear

Firstly, with a large number of precision gears and bearings inside the gearbox, transmission fluid is able to reduce friction between metal components and prevent overheating and wear. Insufficient or deteriorating transmission fluid may quickly shorten the whole transmission life.

Facilitates Shifting

Second, in an automatic transmission, the fluid transmits torque through a hydraulic system to achieve shifting and power output. It is noted that changes in fluid viscosity or blockage of impurities may result in delay, stall or inability to shift.

Maintains Cleanliness

Third, transmission fluid circulation removes heat and dissolves metal debris and impurities, keeping the system clean and healthy. Oil deterioration may gradually reduce heat dissipation, causing the gearbox to overheat, and even damaging internal parts.

Prevents Corrosion

Fourth, special additives in the transmission fluid can prevent further rust and corrosion of metal parts during long-time use. The maintenance cost of gearbox failure may be as high as hundreds of dollars, far exceeding the cost of the regular one.

Preparation of Checking Transmission Fluid

Before getting prepared for checking transmission fluid, you need to know when these fluids show the needs to be checked for specific problems.

After noticing these abnormal states, you can prepare the following tools and materials for further checking of transmission fluid.

To begin with, park the vehicle on flat, dry ground to ensure that the car is level to avoid inaccurate oil level measurement due to slope.

Then, if the vehicle has just been driven, it is recommended to wait more than 30 minutes for the transmission fluid temperature to drop to a normal level (usually 40°C-60°C). Overheated fluid may result in high oil level readings and a risk of burns.

Moreover, you have to prepare a dipstick or inspection bolt depending on the vehicle model; transmission fluid collection container used to pick up old oil or oil spilled during inspection. And remember to wear gloves and goggles in order to prevent irritation and fluid splashing.

Last but not least, tools like jacks and safety brackets (if lifting a vehicle) is essential for you to check the transmission oil level under the chassis. And a flashlight will help you observe the fluid condition in a low light environment easier.

Step-by-step Guide of Checking Transmission Fluid

After adequate preparations of both basic knowledge and tools, it is time to check the transmission fluid step by step.

Consult User Manual

First, consult the user manual to confirm the transmission fluid model, specification and replacement cycle. Transmission fluid requirements may vary from vehicle to vehicle, for example:

Automatic transmission fluid (ATF) : usually labeled "DEXRON", "Mercon", etc.

Manual transmission oil: may be gear oil (e.g. 75W-90).

CVT transmission fluid: Special oil is required.

Check Fluid Level

Second, determine the location of the transmission fluid check port (usually located on the transmission housing). Then, pull out the dipstick or unscrew the check bolt, wipe it clean, reinsert it, and pull it out again to check the oil level. And the fluid level should be between the "MIN" and "MAX" marks.

Inspect Fluid Quality

Third, as we have discussed previously, observe the fluid color (should be clear red or amber), smell (no burnt taste), and viscosity (no unusually thin or thick). If the fluid level is insufficient, it needs to be replenished to the standard range. Or if the oil is cloudy, smelly or exceeds the replacement cycle, replace it with new oil in time.

Lastly, wipe tools and inspection ports with a cleaning cloth to avoid oil residue. And remember to pour the old transmission fluid into a special container and turn it over to a regular recycling point to avoid polluting the environment.

FAQs

How often should we check transmission fluid?

Recommended frequency of inspection:

Manual transmission: Check once every 10,000 kilometers, thoroughly replace 60,000-80,000 kilometers.

Automatic transmission: check once every 10,000 kilometers, thoroughly replace 80,000-100,000 kilometers.

And there are some special cases that need to shorten the cycle:

Harsh conditions: long-term high-speed driving, frequent rapid acceleration/braking, long-term congestion or high load conditions, it is recommended to check every 5000-8000 km.

Model difference: Some Japanese models or models that emphasize fuel economy are recommended to be replaced about 40,000 kilometers.

Oil type: Dual clutch (DCT) and CVT transmission due to the complex structure, it is recommended to shorten the inspection interval according to the manufacturer's requirements (some models need to check every 5,000 kilometers).

What is the difference between checking transmission fluid and engine oil?

The two situations have significant differences in inspection methods, oil properties and replacement cycles.

For Inspection methods, it is necessary to preheat the vehicle and change the gear when checking transmission fluid, and the fluid level reading should be carried out in the state of oil flow. While checking engine oil, it is usually operated in the cooling state of the engine, directly pulling out the oil gauge to observe the oil level and oil quality.

For oil properties, transmission fluid is specially designed for transmission, focusing on wear resistance and shear stability, high viscosity to meet the needs of gear lubrication. But for engine oil, this kind of medium needs to take into account lubrication, cooling, cleaning, rust prevention and other relevant multiple functions, viscosity depending on the engine type (such as naturally aspirated/turbocharged).

For replacement, the cycle of transmission fluid is longer, generally 60,000 km to 120,000 km (depending on the model and the use condition). while for engine oil, the replacement cycle is shorter, usually 5,000 km to 10,000 km (fully synthetic oil can be extended to more than 10,000 km).

Does transmission fluid checking require a professional technician?

Whether the transmission fluid inspection must be done by a professional technician depends on the model design and checking method.

Here are some cases suitable for self-operated conditions, like vehicle models with dipsticks (e.g., most Japanese cars) and models with viewing holes.

And for special conditions requiring professional technicians to operate, it is mainly including some automotive models without dipsticks (such as some German and American cars), or maintenance needing complex inspection requirements. For instance, sometimes the car has to adopt a pressure test, which is necessary to inject pressure gas or liquid into the gearbox to observe the leakage situation, requiring professional equipment and technology. Or the fault diagnosis instrument reads the fault code, which can detect the problem of the transmission control system and requires a professional technician to interpret the result.

The End

Although this is only a small part of automotive maintenance, it is crucial to ensure the proper operation of your car. Remember, regular inspection and maintenance is the most effective way to prevent vehicle failure and extend the service life.