Everything You Need to Know About Transmission Fluid
There are many important fluids that flow in and around your car’s engine. All of them are important: engine oil, coolant, transmission fluid and brake fluid. There’s even a reservoir of washer liquid for your windscreen. All of these fluids need to be checked, changed, topped up and/or flushed regularly, but they also need to be understood.
Today we are looking at transmission fluid, offering you all the key information you need to know about this critical liquid and what it does for your car.
What is Transmission Fluid? What Is Its Function?
Typical transmission fluid is a special lubricating fluid made first from a base oil and then finished with a combination of various additives. Whether your car has a manual or an automatic transmission, there are many moving and interlocking parts. These need to be well lubricated in order to keep the transmission running smoothly.
The main function of transmission fluid is to maintain this lubrication and keep all the many parts of the manual or automatic transmission moving. You can find where your transmission fluid is stored in your engine by looking for the transmission fluid dipstick. It’s typically a dark red colour when it’s brand new, but shifts to brown/black as it gets older and used.
Why Does Transmission Fluid Need to Be Changed?
Besides the lubrication, transmission fluid also dissipates heat in that critical system. A lubricated and not overheating system is one that is working properly and continuously. When transmission fluid is left in the system over time, then the result is an ever-decreasing efficacy. It’s the same thing that happens to your engine oil.
It changes from a rich dark red colour when brand-new to a more contaminated-looking brown or blackish one. This is caused by the many contaminants and other particles that the fluid picks up over its lifetime. For this reason, we have to flush it out because we need fresh transmission fluid for it to be effective.
How Often Does Transmission Fluid Need to Be Changed?
It does vary from car to car, and transmission to transmission, but the general rule is that transmission fluid will need changing every 30,000 to 60,000 miles. If you do a lot of towing or heavy-duty actions in your vehicle, then you will likely be at the lower end of this range. If you only drive your car for commuting, school runs and common everyday tasks, then you’ll be at the higher end.
How Does a Mechanic Change Transmission Fluid?
A mechanic will use the following several steps to change your transmission fluid:
Step 1: The car is raised up with a jack or car lift to provide easy access to the transmission pan.
Step 2: They place a pan, bucket or other receptacle under the pan to catch the old fluid when it’s opened up.
Step 3: The pan can be opened up by loosening the bolts around it, after which the transmission fluid will quickly come running out.
Step 4: Once all the old fluid has been drained out, the transmission pan has its filter and gasket put back in place and then is screwed back in place.
Step 5: Next, the car is lowered and the bonnet popped open. The transmission dipstick is removed, and new transmission fluid can be funnelled into the reservoir via the transmission fluid spout.
Step 6: The mechanic replaces your dipstick, closes the bonnet and the job is done.
Can You Change Transmission Fluid Yourself?
The process described above may seem deceptively simple to some, but it’s not something that is recommended as a DIY task unless you have some prior experience. As a first timer, changing the transmission fluid can be risky because you may not put the right amount back in, or you may replace the gasket/filter in the wrong way. There are a few critical things that could go wrong.
What Are the Signs That Your Transmission Fluid Needs Changing?
Sign 1: Transmission Fluid Has Gone Dark Brown or Black
New transmission fluid is a rich red colour, and over time it shifts towards a dirtier brown colour. You can inspect it on the transmission fluid dipstick to see what the colour and condition of the fluid is currently.
Sign 2: You’re Having Trouble Gear Shifting
Do you notice some lag between gear shifting, or even gear “slipping” which is where you might apply acceleration but feel almost no power boost? These are signs that the fluid isn’t doing its job of lubrication and keeping the parts moving.
Sign 3: You See a “Check Engine Light” or “Transmission Temperature” Light
When your transmission fluid gets older, it loses its ability to dissipate heat in the transmission. You’ll see a warning about this on your dash, either in the form of the “Check Engine” light or in the form of the “Transmission Temperature” warning light.
Sign 4: Transmission Fluid Leak
When you inspect the dipstick to see the colour and condition of your transmission fluid, take a moment to also check the level. If the level has dropped quite low then it could be the sign of a leak. Look in your engine bay and under your car for signs of red transmission fluid leaking away. If it has been a long time since your last transmission fluid change, then some will have disappeared through typical wear. Sudden drops, however, indicate a leak.
How Much Does It Cost to Change Transmission Fluid?
The typical price for a transmission flush is £150 to £200, and possibly as high as £400 if you’re driving a high-end brand. If you have experience with car maintenance, it can be a neat way to save some money by flushing the transmission fluid yourself. It’s not a complex job but does take a little prior knowledge. Ultimately, it’s still safest when left to the professionals.
Don’t Forget Your Transmission Fluid!
Most drivers remember their engine oil and windscreen washer fluid, but tend to forget about transmission fluid. It’s just as important as your other engine fluids, so use your new knowledge and ensure that your transmission fluid remains in good health at all times.