Transmission fluid is a slippery liquid that acts as a lubricant for all of the moving parts inside your transmission. In an automatic transmission, this fluid also serves as a coolant and a viscous fluid that transmit power from the engine to the transmission.
Changing automatic transmission fluid is best left to a mechanic equipped with a transmission flusher, which replaces the fluid more thoroughly than you could achieve with gravity alone. Varieties of fluid are used for different transmissions. Automatic transmission use something called – shockingly – automatic transmission fluid. Manual transmission use a variety of oils: regular motor oil, heavyweight hypoid gear oil or even automatic transmission fluid in some cases.
Should I do this service when it’s recommended?
Yes, definitely, regardless of whether you have a manual or an automatic transmission.
Manual: Hyundai recommend that manual transmission fluid to be changed every 20,000 km or 1 year whichever occurred first. Under heavy duty use, some manufactures suggest changing transmission fluid <20,000 km or 1 year.
Automatic: Service interval for an automatic transmission varies from every 20,000 km to never. Hyundai typical service interval is 20,000 km to 100,000 km depending on the driving condition. Changing it more often does no harm. Some Hyundai models (e.g. Matrix & Getz) are required to replace auto oil filter before changing / flushing the automatic transmission fluid.
Why do I have to do this?
Manual: In a manual transmission, the problem is not so much the fluid degradation, but rather fluid contamination. This contamination occurs over time as the synchronizers, bearings and gears in the transmission wear out. The resulting metal particles then float around in the lubricant. And we all know that oil with microscopic particles of metal in it does not lubricate as well as clean oil. So if these contaminants are not drained out, they will shorten the life of your transmission.
Automatic: Because more heat is generated in an automatic transmission, automatic transmission fluid actually degrades and breaks down with use. In additional, like in a manual transmission, automatic transmission fluid will also become contaminated with worn bits of the transmission. If these contaminants are not drained out, they will shorten the life of your transmission.
What happened if I don’t do this?
If you don’t change the transmission fluid on schedule, you’ll be lubricating your transmission with metal shavings and other contaminants. This will shorten the transmission’s life. The result could be a hefty boat payment to your mechanic. In other words, changing your transmission fluid at the correct interval is a good investment.
Is there any maintenance required between intervals?
Yes. It’s important to regularly check the transmission fluid level between service intervals. Letting your car run low on transmission fluid can cause the transmission to shift improperly – or not at all. It also can harm the internal parts of your transmission, which will not be properly lubricated. Unfortunately, you may not hear any noises or have other clues that your transmission is low on fluid, until it’s too late. So it’s important to get it checked.
Here’s how you can check your transmission fluid:
Manual: Checking the transmission fluid in a manual transmission can be difficult. If you own a car with a manual transmission, we suggest that you ask your mechanic to check the fluid level when your car is up on the lift during an oil change. It takes just a minute.
Automatic: If you own a car with an automatic transmission, your car will have a dipstick for this purpose. Be careful not to make the common mistake of confusing the transmission dipstick with the crankcase dipstick. For most cars, checking the automatic transmission fluid consists of pulling the transmission dipstick out while the engine is warmed up and running and with the transmission in park. We suggest that you check your owner’s manual, however some manufactures may have a different procedure.
Of course, always check your fluid level if you notice a leak of any kind.
Hyundai Tip: Unlike engine oil, transmission oil doesn’t burn up. So if you’re low on transmission fluid, you almost certainly have a leak.