75W-85 Axle Formulations for Commercial Vehicle Applications

Lower viscosity commercial vehicle axle fluids are entering the market, but do they really provide the protection that heavy duty vehicles demand? The right lubricant with a balanced additive package can actually provide both fuel economy and adequate equipment protection. Afton expert Chip Hewette, a Senior Engineering Specialist, explains what you need to know about 75W-85 formulations:


Q: What is causing the shift to using low viscosity fluid for heavy duty vehicle applications?

The automotive industry is continuing to work to improve fuel economy while also extending equipment life and minimizing costs. Longer service intervals are desired while lower lubricant volumes in the sump, increased speeds and higher operating temperatures have been observed. These new conditions require a lower viscosity fluid with the proper ability to protect the equipment and maximize up-time.  

Q: How has the drive for increased fuel economy impacted the role of an axle lubricant?

The drive for fuel economy and efficiency has led to many changes in equipment, requiring axle lubricants to address new challenges:
  • Smaller axle sumps for cost savings and weight reduction
  • Less fluid volume in the sump and lower fluid viscosity to reduce churning losses
  • Higher operating temperatures resulting from less air flow from aerodynamic designs of newer trucks

Q: What are the key benefits of 75W-85 fluids?

75W-85 fluids deliver several key benefits for customers:
  • Fuel economy
  • Improved oxidative stability
  • Reduced churning losses
  • Increased power transfer efficiency
  • Enhanced low-temperature flow
  • Robust durability

Q: What are the results of using thinner fluids, specifically relating to axle protection?

Axles transfer engine power to the rear wheels with a small gear rotating against a larger gear. When the viscosity of the lubricant is reduced, it is more likely that these gear metal surfaces contact as they mesh together. This changes the required additive strength to adequately protect expensive gears and bearings. A thinner fluid means the gears operate in a different and more strenuous lubricating regime. Although efficiency can be gained with thinner fluids under severe service conditions, additive technology must evolve to provide needed protection for gears, bearings, and axle seals.

Q: How are 75W-85 fluids addressing the evolving needs of the axle market?

75W-85 viscosity fluids in axles are used in certain applications today, but to make a transition from higher viscosity fluids, it is paramount to ensure the formulation is robust enough to deliver adequate protection. Most often, such 75W-85 formulations employ synthetic base stocks that generate longer drain intervals and superior oxidation life.

Afton Chemical has 75W-85 formulations that have been lab and field tested for proven performance.

Q: Specifically, how does Afton approach helping customers formulate a low viscosity lubricant to meet the changing needs of the axle market?

Afton assists customers with a four-step approach:
  • Selecting the most appropriate additive for the application
  • Identifying the optimal base stocks and thickeners for market value
  • Guiding the customer with specific blend information, detailing viscosities, and low-temperature performance
  • Confirming tests to validate the lubricant meets the needs of the customer

Q: What are Afton’s 75W-85 formulation product offerings?

Selected additive technology can be formulated in this viscosity grade, including but not limited to:
Product name  Description  Application
HiTEC®  3339  Multifunctional gear oil additive GL-5 and industrial capable for light-duty & heavy duty axle lubricants
 HiTEC® 369  Automotive gear oil additive J2360 performance for use in light-duty & heavy-duty axle lubricants
 HiTEC® 385  Premium, multifunctional gear oil additive
J2360, MT-1 and limited slip performance for use in light-duty & heavy-duty axle and manual transmission fluids
Industrial gear capable
 HiTEC® 355  Premium, extended-drain gear oil additive J2360 performance with extended-drain capabilities (500K miles) for heavy-duty axle fluids
 HiTEC®  3301  Axle fluid viscosity modifier Multifunctional and shear stable viscosity modifier for automotive gear lubricants
 HiTEC® 5760  Premium axle fluid viscosity modifier Highly shear stable olefin copolymer VI improver for automotive gear lubricants
 HiTEC® 008  Seal swell agent Effective solubility agent for synthetic fluids with positive impacts on seal compatibility and low temperature properties in automotive and industrial gear lubricants



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