LDU Unit Surpasses One Million Kilometers Without Overhaul
Experts from Sveta Nedelja engineered their own graphite seal and achieved the mileage Elon Musk talked about back in 2017, but for a different powertrain.
Experts from Sveta Nedelja engineered their own graphite seal and achieved the mileage Elon Musk talked about back in 2017, but for a different powertrain.
Croatian company EV Clinic, an independent electric vehicle laboratory from Sveta Nedelja, announced in early June that a Tesla Large Drive Unit (LDU) powertrain, reconditioned using their own process, has surpassed one million kilometers. The motor was never reopened, disassembled, or overhauled.
"One Tesla LDU. Original motor. One million kilometers on a single unit. No overhaul, no disassembly, no re-repair. Same seal, no coolant intrusion, still spinning and still driving every day," EV Clinic stated when presenting the result.
This concerns the first generation of Tesla's Large Drive Unit powertrain, which was installed in certain versions of the Model S and Model X. According to EV Clinic's experience, the key weak point of this assembly is the rotor sealing. When the seal fails, coolant leaks toward the stator and other electrical components, which can lead to costly failures.
Some independent workshops resort to the so-called "coolant delete" solution-removing part of the rotor cooling system so that fluid can no longer reach through the problematic seal. EV Clinic strongly disagrees with this approach, arguing that it does not address the root cause but merely adjusts the cooling conditions of the entire powertrain system. Based on their experience, eliminating rotor cooling can lead to increased thermal stress on the stator, especially on the windings, which could cause a new issue elsewhere.
Instead of removing the cooling, EV Clinic experts decided to engineer their own solution. Their process includes treating the shaft sealing surface, installing a graphite mechanical seal, replacing bearings and O-rings, and testing the drive unit on a special rig before returning it to the vehicle. The intention is to preserve the factory rotor cooling design while eliminating the part that allows coolant to reach the motor's electrical section.
They named their kit the eDrive Holy Grail Kit. As early as the seventh month of 2025, data was published on the same drive unit after 560,000 kilometers, noting that the oil had been changed and that there was no noticeable wear on the bearings or signs of coolant leakage through their graphite seal.
EV Clinic clarifies that the claim of one million kilometers "without service" does not mean that nothing was touched during the entire period-the mentioned oil change was performed at 560,000 kilometers. What they emphasize is that the same drive unit reached one million kilometers without the need for new disassembly, overhaul, or motor rework, and with the same seal that was installed.
Confident in their solution, EV Clinic offers a two-year warranty with no mileage limit on their reconditioned LDU units.
The story gains an additional dimension when recalling Elon Musk's statement from 2017. At that time, Tesla's CEO mentioned the new generation of the Model 3 powertrain, saying it was designed for durability exceeding one million miles, which is approximately 1.6 million kilometers. This is not the same drive unit that EV Clinic worked on-the Croatian experts worked on the older LDU version from the Model S and X.
Nevertheless, EV Clinic presented their result as the realization of the idea of million-mile durability for electric powertrains. "Elon promised one million kilometers and never delivered. Twelve years later, EV Clinic did," they stated.
It is important to note that this is only EV Clinic's statement-the result was not presented as an independently verified test by a third party, but rather as their own validation of the drive unit under real-world conditions. Behind this claim stands a concrete motor that, according to their information, is still in daily use even after one million kilometers.
EVC Research & Development is registered in Croatia, with its headquarters and workshop in Sveta Nedelja, and is described as an independent laboratory for electric vehicle research and development, as well as a center for their disassembly and analysis. Their approach for years has been based on attempting to repair expensive electric components that manufacturers or authorized service centers typically replace as whole assemblies.
If the real-world data is accurate, the result is hard to ignore: the same core of the drive unit, the same construction after their modification, and one million kilometers driven without the need for re-disassembly and motor overhaul. For a small Croatian development team, that is a rather impressive figure.
