Oil Drain Plugs, Filler Caps & Dipsticks
About Oil Drain Plugs, Filler Caps & Dipsticks
Drain plugs, filler caps and dipsticks are the access points for changing and checking engine oil. They are small parts, but a stripped drain plug thread, a cap that works loose or a missing washer will leak oil, so they get replaced after damage as well as swapped for a different look.
For a drain plug, the thread size and pitch must match the crankcase, and the sealing washer matters as much as the plug. Many washers are crush type and meant to be replaced, so check the manual. A magnetic drain plug collects fine steel particles from the oil, and the listings include magnetic plugs for KTM, Husqvarna and Gas Gas models. Filler caps are listed with thread sizes such as M20 x 1.5, M20 x 2.5 and M27 x 3.0, which you can find on the old cap or in the manual. Colored caps still need the right thread and a good O-ring. A dipstick must be the right length for your model.
Brands here include Bolt, Colony, Zeta, HardDrive and Drag Specialties. Pick your machine in the Ride Finder at the top of the page. Related categories include Engine Covers and Brackets & Hardware, both part of Engines & Engine Parts.
FAQs on oil drain plugs, filler caps and dipsticks
Should I replace the drain plug washer at every oil change?
Often yes. Many washers are crush type, made to compress once, and a reused one can leak. Some plugs have a reusable seal, so check the owner's manual or the listing for the right practice on your bike.
How tight should an oil drain plug be?
Tighten it to the torque in the service manual, using a torque wrench. Too loose and it leaks, and too tight can strip the thread in the case, which is often aluminum and expensive to repair. Do not tighten by feel.
What does a magnetic drain plug do?
A magnetic drain plug holds fine steel particles from the oil against a magnet instead of letting them circulate. Looking at what collects on it at each oil change can show you how the engine is wearing.
How do I find the thread size for an oil filler cap?
Check the old cap or the owner's manual, or compare it with the sizes in the listing. A size such as M27 x 3.0 means a 27 mm diameter with a 3.0 mm pitch, and both numbers must match.
Are colored oil caps only for looks?
Mostly, yes. The color is a finish, but the cap still has to fit the thread and seal properly, so check the O-ring and the fit. A dirt bike cap that does not seal can throw oil onto the engine.
