A gearbox oil leak appearing eighteen days after clutch replacement creates a strong presumption of garage liability, because clutch service typically requires removal or displacement of the gearbox, which disturbs seals and gaskets that are common failure points. The most probable culprits are the input shaft seal (which sits directly behind the clutch release bearing), driveshaft seals, or improperly tightened drain or fill plugs—all of which would have been handled or accessed during the job. The short eighteen-day window between repair and leak onset suggests causation rather than coincidence.

However, the garage may argue that a seal was already worn and failed by chance after the work. To establish clear responsibility, you must first identify the exact leak source. Stop driving if the leak is significant, as low gearbox oil causes rapid transmission damage. Take photographs or video of the leak location and fluid type, and check your invoice to see which seals or gaskets were replaced or inspected. Return to the garage promptly with this evidence and request a written inspection report identifying the leak source.

If the leak originates from a component that would have been removed, disturbed, or refilled during the clutch job—particularly the input shaft seal or driveshaft seals—the garage should remedy it at no cost under their workmanship warranty. Most reputable shops will accept this responsibility if the correlation is clear. If they refuse and the leak is demonstrably from their work area, consider an independent inspection and keep all documentation for a potential claim. The burden of proof rests on establishing that the leak source was touched during the repair.