Oil leak on a Honda NC750X 2026

Poorly tightened drain plug / filter

Confirmed diagnosis: an oil leak caused by a loose drain plug or oil filter, or a crushed/missing seal -- typically right after an oil change. This is the simplest and most common cause of a sudden oil leak, and thankfully the easiest to fix. The drain plug seals the bottom of the crankcase with a seal (an aluminum or copper washer, or an O-ring) that gets crushed with every tightening and ideally should be replaced at every oil change; the oil filter (spin-on or cartridge type) seals with an O-ring. Under-tightening, over-tightening (which deforms the seal or damages the threads), a reused, already-crushed seal, or a double seal (an old filter seal left stuck in place) all cause seeping. The approach: retighten to spec with a new seal, or redo the filter's seal. This is a Basic-level job. Risk level: low. Budget: a drain plug seal costs a few cents to a few euros, an oil filter runs 8 to 20 euros. Important: respect the torque spec (don't force it on an aluminum case, or you risk stripping the threads -- an expensive repair), use a new seal, and check there isn't a double seal stacked at the filter. Afterward, clean the area, check the oil level, and watch for any further seeping. This tool helps you understand what's going on -- it doesn't replace a certified mechanic.

How to make the repair yourself

🟢 Within reach of any rider: no advanced mechanical skill or specialised tooling needed.

1. 1With the engine warm or cold, clean and dry the area around the drain plug and oil filter, then pinpoint exactly where the seeping is coming from (plug, filter seal, or both).
2. 2Get a new drain plug seal (washer of the correct size/material) and, if the filter is at fault, a new filter and oil for the top-up.
3. 3For the plug: first check it isn't simply loose. If you remove it, place a drain pan underneath (oil will run out), clean the plug and its sealing surface, fit a NEW seal, and retighten to the manufacturer's torque spec (not too little, not too much, so you don't damage the case threads).
4. 4For the filter: make sure there isn't an OLD seal left stuck to the mounting surface (a classic cause of a leaking double seal). The mounting surface needs to be clean.
5. 5If you're replacing the filter, lightly coat the new filter's O-ring with fresh oil, and tighten to spec (often hand-tight until the seal contacts, then about 3/4 turn -- check your model).
6. 6Recheck the oil level on the dipstick (bike upright) and top up as needed after accounting for what leaked out.
7. 7Thoroughly clean any oil residue off the lower engine (so you can spot any new leak), then start the engine briefly.
8. 8Watch the area and the ground under the bike after starting and after a few rides: no new seeping confirms the fix. If it leaks again, the threads or mounting surface may be damaged -- have it checked.