What Transmission Do I Have?
The GM Hydramatic 6L80 transmission was designed to provide optimum fuel economy without sacrificing vehicle performance. To meet stringent fuel economy mandates, this 6 speed automatic transmission uses a special output gear arrangement, with a wide 6.04:1 gear ratio to allow for strong acceleration in the lower gears and low RPM cruising when on the highway. And as you might imagine, it takes a lot of 6L80 transmission fluid to keep this complex gearbox cool.
So, how much fluid does a 6L80 transmission hold?
The 6L80 transmission fluid capacity depends on which torque converter is installed. Most full-size pickup trucks and SUVs have a 300 mm 6L80 torque converter, while light duty applications often have the 258 mm torque converter.
- 6L80 fluid capacity with the 258 mm torque converter: 9.7L/10.25 qt
- 6L80 fluid capacity with the 300 mm torque converter: 11.9L/12.57 qt
- 6L80 transmission fluid type: DEXRON VI
What transmission fluid does
Believe it or not, the primary role of automatic transmission fluid is not lubrication. It’s cooling. Every time the ATF passes over the moving parts, it soaks up the heat that’s created by the friction of those moving parts. It then carries that heat away and flows up to the radiator where it passes through a transmission cooler and releases the heat.
Importance of servicing a transmission
The 6L80 transmission is a very complicated gearbox, and the moving parts inside of it must be kept cool and lubricated to prevent premature damage. Automatic transmission fluid wears out just like engine oil, and must be changed regularly. The average recommended service interval is around 30,000 miles. But doing it sooner is likely to help you extend the service life of your transmission.
As the 6L80 ATF wears out, it becomes thin and dark colored. In this state, the amount of heat the fluid is able to move gets significantly reduced. This means there will be considerably more friction between the moving parts, increasing the likelihood of premature damage. These are some of the 6L80 transmission problems that can result from a lack of proper maintenance:
- Failed transmission solenoids
- Failed clutch packs
- Torque converter failure
- Seals began to fail
- Metal parts like gears and clutch drums can crack
Click here to learn more about what heat damage does to your transmission.
What to do when changing the transmission fluid won’t fix the problem
It’s not unusual to perform a transmission fluid change in an effort to fix 6L80E transmission problems like slipping or failed gear engagement. Sometimes a clogged transmission filter or dirty transmission fluid can be the root cause of some of these problems. But more often than not, there can be other issues at play.
For example, it’s not uncommon for the 6L80 3-5-R clutch drum to crack and cause slipping or failed gear engagements. But it could also be the 6L80 TEHCM. There are also a number of design flaws with this transmission that can seriously impact reliability if it’s left in stock form.
If you service the transmission and the problems persist, it may be wise to replace the transmission if you want to extend the service life of the vehicle. Here are your options:
Buy a Used 6L80 Transmission
If you wanted to save some money, you could go down to the local junkyard and buy a used 6L80 transmission. But keep in mind, it’s coming out of a wrecked or otherwise totaled vehicle. This means you don’t know how it was maintained, if it was abused or what the condition of the internal components really are. So you have no way of knowing if you are going to get 30 miles or 30,000 miles out of it. And that replacement warranty you get from the junkyard isn’t going to cover the labor cost that you’ll have to pay a mechanic to install a replacement transmission if the first used 6L80 breaks.
Buy a Rebuilt 6L80 Transmission
If you don’t want to risk future problems from a used transmission, then you might consider buying a rebuilt 6L80 transmission from a mechanic or transmission shop. In this scenario, they basically take your existing transmission and replace all of the main seals clutches and other “wear parts”. A rebuilt 6L80 transmission is obviously better than a used one. However, most mechanics and repair shops don’t have the experience and equipment to inspect every single component for signs of damage, warping and any other condition that might cause the parts to fall below the original manufacturer’s specifications. Plus that rebuilt transmission warranty may only be honored by a few local transmission shops.
Buy a Remanufactured 6L80 Transmission
Unlike a rebuilt 6L80 transmission, a remanufactured 6L80 transmission has been completely disassembled and then re-engineered on an assembly line. Each component is inspected, cleaned, and reconditioned by a technician that specializes in that particular stage of the process. All of the critical elements including the case, gears, valve body, shafts, pumps, and the torque converter are tested to ensure that they meet original equipment (OE) tolerances and standards. And any part that doesn’t meet the original specifications is either machined until it does or replaced with a brand new part.
Once all of the components meet specification, they’re sent down an assembly line and the transmission is reassembled. The reman 6L80 transmission is then put on a dyno machine which simulates real-world driving through a software program called C.A.R.S. This allows any leaks and imperfections to be discovered and dealt with before the transmission leaves the factory.
Another benefit of a remanufactured transmission are the updates and upgrades it receives. Once a certain vehicle model has been in production for a few years, small issues with the design are discovered and solutions are implemented. It may be more robust friction materials, stronger seals, stiffer springs, or number of other things. These changes are immediately applied to the new models still in production, and Technical Service Bulletins (TSB’s) are sent to dealers so they know how to deal with problems that may arise. Transmission remanufacturing companies like Street Smart Transmission also get these TSB’s, and implement the changes on their assembly line as well.
What Transmission Do I Have?
If you’d like to learn more about getting a remanufactured 6L80 transmission from Street Smart Transmission, click here.
