Dexron III Is a General Motors Automatic Transmission Fluid Specification That Some Vehicles Specify as Power Steering Fluid
Dexron III, also written Dexron 3, is a General Motors (GM) specification for automatic transmission fluid (ATF). GM upgraded to Dexron VI with the start of 2006 vehicle production.
What Is Dexron III Power Steering Fluid?
Dexron III power steering fluid is an automatic transmission fluid that meets the GM Dexron III specification and is used in power steering systems where the manufacturer specifies it. Dexron III is a General Motors trademark for qualified automatic transmission fluids. GM licenses the Dexron designation to fluid vendors. Examples include Valvoline ATF DX-3, a mineral-based fluid, and MOGAS ATF Dexron III-H, a red fluid.
Is Dexron III Still Made?
GM lists Dexron III as obsolete. Valvoline, Amalie, and MOGAS still sell fluids rated to the Dexron III-H specification, according to their product data sheets.
Can You Use Dexron III as Power Steering Fluid?
Dexron III is suitable as power steering fluid only where the vehicle manufacturer specifies it. Valvoline, Amalie, and MOGAS data sheets list power steering systems that specify Dexron III. Lubriplate does not recommend its Dexron III/Mercon fluid as a power steering fluid unless the manufacturer specifies it. ACDelco recommends only the power steering fluids that the owner’s manual identifies.
For related reading, see Rack Steer: How It Works, 4 Assist Types, and 5 Failure Symptoms. The same maintenance context also connects with Rack Steer.
Which Vehicles Specify Dexron III for Power Steering?
Owner posts quote 2012 and 2015 Toyota 4Runner manuals that list Dexron II or III ATF for the power steering system.
What Does GM Specify for Power Steering?
GM sells ACDelco GM Original Equipment Power Steering Fluid, part 19329448, for power steering systems. GM bulletin 04-07-30-037D, as quoted on forums, directs power steering systems to GM fluid labeled Power Steering Fluid.
What Are the Specifications of Dexron III Fluids?
Dexron III fluids list kinematic viscosity at 100°C between 7.15 and 7.5 mm²/s on data sheets from 4 manufacturers. The table compares 3 Dexron III products by viscosity and viscosity index. Amalie lists cSt, which equals mm²/s.
| Product | Viscosity at 100°C (mm²/s) | Viscosity at 40°C (mm²/s) | Viscosity Index |
|---|---|---|---|
| Valvoline ATF DX-3 | 7.2 | 35.07 | 177 |
| Amalie DX III-H/M ATF | 7.2 | 34.5 | 170 |
| MOGAS ATF Dexron III-H | 7.15 | 37.09 | 159 |
What Is the Low-Temperature Viscosity of Dexron III Fluids?
Brookfield viscosity at minus 40°C is 12,800 cP for MOGAS, 18,900 mPa·s for Motorex, and below 20,000 cP for Amalie. One cP equals one mPa·s.
How Does Dexron III Differ From Dexron VI?
Dexron VI replaced Dexron III in GM transmissions with the start of 2006 production, and GM reports 100% better clutch friction stability and 120% better clutch durability. GM also reports 20% greater oil film thickness and a fill-for-life interval of 100,000 miles for cars and light trucks. Lubrication Engineers lists power steering systems and hydraulic pumps among its Dexron VI applications.
Is Dexron VI Backward Compatible With Dexron III?
In automatic transmissions, yes. GM bulletin 04-07-30-037A allows Dexron VI as a replacement in 2005 and prior models that use Dexron III. GM addresses power steering systems separately, through its fluid labeled Power Steering Fluid.
For a reliable reference point, see NHTSA recalls and vehicle safety.
What Did GM Bulletin PI0620A Find for Power Steering?
GM bulletin PI0620A (October 2015) recommends changing power steering fluid to Dexron VI when replacing the steering gear, to prevent future repairs for a steering gear squeak noise. The bulletin covers 4 points:
- Models: 2008 to 2012 Buick Enclave, 2009 to 2012 Chevrolet Traverse, 2007 to 2012 GMC Acadia, and 2007 to 2010 Saturn Outlook built before July 1, 2011.
- Scope: gear replacements only, not repairs to the pump, cooler, or hoses.
- Procedure: flush with about 3 L (3 qt) of Dexron VI until the draining fluid appears red.
- Caution: no old fluid contacts the new pinion shaft seal.
How Do You Choose Dexron III or Dexron VI Power Steering Fluid?
Choose the fluid by completing 3 checks: match the owner’s manual, confirm the data sheet lists power steering use, and flush old fluid before fitting a new steering gear. The 3 checks are:
- Match the fluid to the owner’s manual specification. ACDelco recommends only manual-identified fluids.
- Confirm the product data sheet lists power steering use. Lubriplate does not list it for Dexron III/Mercon.
- Flush old fluid from the system before fitting a new steering gear. GM specifies this in bulletin PI0620A.
What Do People Also Ask About Dexron III Power Steering Fluid?
Is Dexron III the same as power steering fluid?
No, Dexron III is an automatic transmission fluid specification, and GM sells a separate power steering fluid.
What color is Dexron III?
Dexron III fluids such as MOGAS ATF Dexron III-H are red.
Can Dexron III and Dexron VI be mixed?
GM states that Dexron VI is compatible with former Dexron versions in automatic transmissions, and GM addresses power steering systems separately.
Why did GM recommend Dexron VI in some power steering systems?
GM recommends Dexron VI to prevent repeat repairs for a steering gear squeak noise in certain 2007 to 2012 models.
What Is the Role of Dexron III in Power Steering Systems?
Dexron III is an obsolete GM automatic transmission fluid specification that some manufacturers specify as power steering fluid. Data sheets list kinematic viscosity at 100°C between 7.15 and 7.5 mm²/s. GM replaced Dexron III with Dexron VI starting with 2006 production. The 3 checks are matching the owner’s manual, confirming power steering use on the data sheet, and flushing old fluid before fitting a new steering gear.