Prioritisation will be key: some elements of legacy specifications may have become less relevant over time and can be scaled back or substituted with alternative performance requirements. This requires careful consideration: like deciding which Jenga block to slide out from the lower section of the tower before adding a new block on top.
Stretching functionality The questions are endless. How well will today’s Off-road lubricants perform with electrified systems and how much further can we stretch these lubricants? Could multifunctionality cease to be feasible or commercially necessary? Can EV-optimised lubricants deliver strong enough performance in crucial Off-road areas? Could lubricants become over-formulated in the attempt to adopt additional performance requirements? How much should backward compatibility take precedence over innovation for future needs?
Answering these requires an understanding of which lubricant tests remain most relevant. When formulating a new UTTO or TO-4 oil to meet global market needs, the tests easily add up to over 100. How should these myriad tests be prioritised alongside electrical needs?
Lubricant benchmarking
Afton Chemical has carried out benchmarking to identify and understand where current off-road and EV additive technologies may have performance gaps alongside opportunities for developing solutions. Samples of commercially available multigrade UTTO and monograde TO-4 style lubricants were compared
with blended oils containing either traditional off-road additives or on-road electrified transmission fluid additives. Performance was evaluated using a selection of Off-road and eMobility tests.
Traditional off-road tests included FZG low speed wear and load carrying capacity, D1748 rust, seals compatibility, water sensitivity and friction.
eMobility tests included DKA Oxidation (170°C/192 hrs) with electrical conductivity measured before and after oxidation, breakdown voltage, thermal conductivity and copper compatibility in extended D130 and Afton’s in-house Printed Circuit Board (PCB) test.
Results
Results were as expected in that overall, off-road and eMobility lubricants share some similar requirements, but their key priorities may conflict.
Performance areas where similarities exist are gear protection, elastomer compatibility and low severity copper compatibility, whereas with friction, electrical conductivity and copper protection, their core priorities often conflict.
Friction remains the most complex challenge, with EV lubricants unable to deliver the right balance of durability and static/dynamic performance across different applications. One of the main differentiations between UTTO and TO-4 is friction performance. Avoiding Noise, Vibration, and Harshness (NVH) is critical for UTTO applications, while TO-4 applications tend to favour higher torque
Figure 1: Additive performance requirements
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LUBE MAGAZINE NO.188 AUGUST 2025
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