economics Practical Magic

Electric cars can now use their own coolant—basically their 'blood'—to tell you exactly how much their internal parts are wearing out.

April 13, 2026

Original Paper

EPR Study of Lubricating Oils – SPIONs in Electric Vehicle Transmission Fluid as a Wear Marker

SSRN · 6557893

The Takeaway

By putting magnetic nanoparticles in transmission fluid, engineers can track exactly where and when mechanical wear is happening. This turns the liquid into a sensitive diagnostic tool that can predict a breakdown before it happens.

From the abstract

Electron paramagnetic resonance (EPR) spectroscopy is rarely applied to lubricants, yet it offers unique sensitivity to superparamagnetic iron oxide nanoparticles (SPIONs), a nanometric fraction of wear debris formed in steel-based mechanical systems. In this work, we demonstrated that the broad EPR signal often observed in spent lubricants originates from SPIONs, and not from organic radicals as previously reported. SPIONs were detected in different used lubricants—including EV transmission flu