SAE Viscosity Grades vs. Automatic Transmission Fluids (ATF)
Comparing 2 standards across 15 specifications. 15 key differences identified.
SAE J300 is the universal standard defining engine oil viscosity grades. Multigrade oils (e.g. 0W-20, 5W-30) specify two metrics: a low-temperature Winter ('W') grade governing Cold Cranking Simulator (CCS) and Mini-Rotary Viscometer (MRV) pumpability at sub-zero temperatures (-40°C to -10°C), and a high-temperature 100°C kinematic viscosity (cSt) and High-Temperature High-Shear (HTHS) rating.
Automatic transmission fluids (ATF) are highly engineered multi-functional hydraulic fluids standardized by OEM specifications (GM Dexron VI, Ford Mercon LV, Chrysler ATF+4, Toyota WS, ZF Lifeguard) into stepped planetary, Continuously Variable (CVT), and Dual-Clutch (DCT) fluid formulations with strict kinematic viscosities and friction-modifier curves.
Specification Comparison Table
15 Parameters| Parameter / Spec | ||
|---|---|---|
|
Standardization
|
SAE J300 / ASTM D445 / ASTM D5293 (CCS) / ASTM D4684 (MRV) | — |
|
Winter 'W' Cold Cranking Limits
|
0W: Max 6200 cP @ -35°C | 5W: Max 6600 cP @ -30°C | 10W: Max 7000 cP @ -25°C | 15W: Max 7000 cP @ -20°C | — |
|
Winter 'W' Low-Temp Pumping (MRV)
|
0W: Max 60,000 cP @ -40°C | 5W: Max 60,000 cP @ -35°C | 10W: Max 60,000 cP @ -30°C | — |
|
100°C Kinematic Viscosity (SAE 20)
|
6.9 to <9.3 cSt (mm²/s) — Modern fuel-efficient gasoline engines (0W-20, 5W-20) | — |
|
100°C Kinematic Viscosity (SAE 30)
|
9.3 to <12.5 cSt (mm²/s) — Universal all-around benchmark (5W-30, 0W-30) | — |
|
100°C Kinematic Viscosity (SAE 40)
|
12.5 to <16.3 cSt (mm²/s) — European performance and diesel engines (0W-40, 5W-40) | — |
|
Ultra-Low Viscosity (SAE 16 / 12 / 8)
|
SAE 16 (6.1-8.2 cSt), SAE 12, SAE 8: Ultra-thin oils for next-generation hybrid powertrains | — |
|
Governing Standards
|
— | SAE J311 / GM GMN10060 (Dexron VI) / Ford WSS-M2C938-A (Mercon LV) / JASO 1-A-LV (Japanese OEM) |
|
GM Dexron VI
|
— | Viscosity: 5.83 cSt at 100°C | Fully backward compatible with Dexron II/III | Shear-stable synthetic |
|
Ford Mercon LV
|
— | Viscosity: 5.7 cSt at 100°C | Low-viscosity standard for modern 6-speed and 10-speed (10R80) transmissions |
|
Chrysler / Stellantis ATF+4
|
— | Viscosity: 7.3 cSt at 100°C | High shear-stability Group III synthetic | Mandatory for Torqueflite / 42RLE |
|
Toyota Genuine ATF WS
|
— | Viscosity: 5.4 cSt at 100°C | Low-viscosity 'World Standard' for Toyota/Lexus 6/8-speed automatic transmissions |
|
CVT Fluid (Push-Belt / Chain)
|
— | High metal-to-metal steel belt friction coefficients (NS-2/NS-3, Lineartronic) | NEVER mix with standard ATF |
|
Dual-Clutch Transmission (DCT/DSG)
|
— | Wet-clutch synchronization + high-pressure hydraulic valve bodies (VW G 052 182 / Pentosin FFL-2) |
|
Operating Temperature Limits
|
— | Optimal: 77°C–93°C (170°F–200°F) | Every 11°C (20°F) above 93°C halves fluid life via thermal oxidation |