What Size is the Oil Drain Plug?
2 Answers
Each vehicle model has a different engine, displacement, and consequently, a different oil drain plug. The function of the engine oil drain bolt is: It allows the dirty oil inside the engine to be drained during an oil change. After draining the dirty oil, the drain bolt is tightened to replace it with new oil, serving as a seal. The oil drain bolt can be reused: The oil drain plug can be reused, but the drain plug washer should not be reused. The washer serves as a seal, and the most commonly used washer is an aluminum one because aluminum is softer than steel. When the bolt is tightened, the aluminum washer deforms to fill gaps. However, a used washer has already undergone deformation during installation, making its internal structure denser. Reusing it makes it difficult to compress and deform again, thus failing to provide a proper seal. Therefore, it is best to replace the washer with every oil change.
When I first started changing my own oil, I was particularly curious about the size of the drain plug bolt. After searching around, I realized there's no standard size—it varies by vehicle. Common sizes are 12mm or 14mm, but German cars might use 16mm, and the thread pitch isn't consistent either. On my first attempt, I nearly stripped the threads before learning to check the owner's manual or ask a mechanic. The manual lists exact specs, and searching online by model and year can provide backup options. If info is unavailable, bringing the old bolt to a hardware store for matching is a smart move. Having the correct wrench before starting is crucial—using the wrong size may lead to leaks post-change, creating bigger headaches. Regular oil changes are vital for engine health, but don't overlook this critical detail.
