A Comprehensive Guide to Automatic Transmission Fluids

Learn How Automatic Transmission Fluid Differs From The Other Fluids in Your Vehicle

Automatic transmission fluid (ATF) is a specialized lubricant designed specifically for the needs of automatic transmissions. It differs from other automotive fluids, such as engine oil, coolant, brake fluid, and power steering fluid, in several key aspects:

• Lubrication— Like motor oil, ATF lubricates the moving parts within the transmission, reducing friction and wear.
• Cooling— As bands and clutches engage, they slip and create heat. The ATF helps dissipate heat generated by the gears as well as heat from bande and clutch engagement.
• Hydraulic Function—ATF is a hydraulic fluid that operates clutch pack pistons and band servos, as well as the valves and accumulators.
• Friction Modification— ATF has specific frictional properties that are essential for the proper operation of clutch packs and bands, which engage and disengage to shift gears. The friction modifiers are specific to each transmission to allow limited slip during initial operation and then full stick when fully engaged.
• Anti-Foaming and Anti-Oxidation— ATF contains additives to prevent foaming and oxidation, which can degrade the fluid and impair transmission performance.
• Seal Conditioning— The fluid helps keep seals pliable and prevents leaks.

The Chemical Composition of automatic transmission fluid

ATF has a unique chemical composition tailored to meet the specific requirements of automatic transmissions. It typically includes:

• Base Oils— Highly refined mineral oils or synthetic oils.
• Additives— Including anti-wear agents, detergents, pour depressants, dispersants, friction modifiers, anti-oxidants, anti-corrosion agents, and anti-foaming agents.

Color and Viscosity

• Color— Most ATFs are dyed red to distinguish them from other fluids and to help detect leaks.
• Viscosity— ATF is designed to maintain its viscosity under a wide range of temperatures and operating conditions. This is crucial for ensuring consistent hydraulic pressure and lubrication.

What makes automatic transmission fluid different from motor oil?

Transmission fluid contains some of the same additives as motor oil, such as anti-wear additives, rust and corrosion inhibitors, detergents, anti-oxidants, dispersants, seal conditioners, and surfactants. However, it doesn’t contain nearly the amount of viscosity index improvers and modifiers, cold-flow improvers, high-temperature thickeners, or pour point depressants as motor oil.

What are the different types of transmission fluid?

Each car maker has their own recommended transmission fluid based on the individual transmission. Even though oil companies sell “universal” transmission fluids and transmission fluids that work in “all makes and models,” not a single car maker recognizes these universal fluids. In fact, if you compare the car maker’s fluid specifications to the specifications on the universal fluids, there is NO WAY a single universal fluid can possibly meet all car makers transmission fluid specifications. Some of the specifications are even mutually exclusive.

• ATF+4 The current transmission fluid for Chrysler products. Replaces ATF+3, ATF+2, ATF+
• DEXRON VI The most current transmission fluid for GM vehicles. It is backwards compatible with Dexron III/Mercon
• Mercon V The most current transmission fluid for most Ford, Mercury, Lincoln, and some Mazda vehicles
• Mercon LV The recommended transmission fluid for some Ford(DuratecHE) and Mazda vehicles
• Mercon SP – For the Ford 6R transmission
• Toyota ATF Type T-IV (T4) The fluid for some Toyota and Lexus vehicles. Replaces Type T, Type T-II and Type T-III.
• Toyota ATF WS The fluid for some Toyota and Lexus vehicles with CVT transmission.
• DW-1 The fluid for Honda and Acura (except CVT). Replaces Z1 specification fluid
• Diamond SP-III (or SP3) The fluid for Mitsubishi (including CVT’s), Hyundai and Kia 4-speed automatic transmission.
• Diamond SP-IV (or SP4) The fluid for Hyundai and Kia 6-speed automatic transmission.
• Nissan Matic The fluid for Nissan and Infiniti vehicles
Matic D is for 3- and 4-speed transmissions,
Matic K is for 5-speed front-wheel-drive transmissions,
Matic J is for 5-speed rear-wheel-drive transmissions,
Matic-S fluid supersedes Matic-J fluid.
• ATF-HP The fluid for some Subaru vehicles, except CVT transmissions. 2004 and earlier Subaru vehicles use Dexron III.
• Mazda M5 (MV) The fluid for the Mazda FN4A-EL/Ford 4F27E and Mazda FS5A-EL/Ford FNR5. Also sold as Ford FNR5 fluid. Genuine Mazda M5 is made by Idemitsu Corporation, available as Idemitsu Type-M.
• Mazda FZ fluid The fluid for the SKYACTIV-Drive. Color of this fluid is blue.

Can you use a universal or all-makes, all models of transmission fluid?

NO! NEVER use a universal or all makes and models fluid in your transmission.

Can you mix transmission fluid types?

No

What causes transmission fluid to fail?

High heat is the #1 cause of automatic transmission fluid failure. Stop-and-go driving on hot days, getting stuck, and rocking the vehicle back and forth between drive and reverse all create high heat conditions. Neglecting recommended transmission fluid changes can also cause the fluid to degrade.

When to get a transmission fluid flush?

Follow the recommendations listed in your car owner’s manual. Some carmakers don’t list a change interval, while most of the newer CVT transmissions require an automatic transmission fluid change as often as every 30,000 miles.

Read this post on transmission fluid flushes

©, 2018 Rick Muscoplat