Bourne HPP M33x3.5mm Aluminum Oil Cap for Honda/Acura

Bourne HPP M33x3.5mm Aluminum Oil Filler Cap - Honda/Acura

The oil filler cap is one of those parts you never think about until the factory one lets you down. It seals the top of your valve cover where you add oil, and on most Hondas and Acuras it's a plastic cap with a rubber seal. That's fine when it's new, but heat and age are hard on it. The rubber hardens and starts to weep, the plastic gets brittle, and the cap itself gets harder to grip with oily hands. This Bourne HPP cap is a billet aluminum replacement that seals better, grips better, and happens to look a lot better doing it.

A Viton Seal That Survives the Heat

The real functional upgrade here is the O-ring. Bourne uses a high-temperature Viton O-ring instead of standard rubber, and that matters because the top of the engine is exactly where a seal gets cooked. Ordinary rubber hardens and shrinks over heat cycles, which is why old oil caps start to seep. Viton holds its properties at much higher temperatures and resists that breakdown, so you get a seal that stays tight and keeps doing its job long after a rubber one would have gone hard. It threads in to OEM spec with the correct M33 x 3.5mm pitch, so it seals against your valve cover exactly the way the factory cap did, just better.

Built With the Track in Mind

Two details set this apart from a plain dress-up cap. There's a 22mm hex machined into the top, so if the cap ever gets stubborn you break it loose with a socket or wrench instead of fighting it with greasy fingers. And there are lock wire holes drilled for safety wire, which is the detail that matters if you run track days or wheel-to-wheel. A lot of tech inspections want the oil cap safety-wired so it can't vibrate loose and dump oil onto the track, and this cap is ready for exactly that. Even if you never wire it, it's nice to know the option is built in.

Machined and Finished to Show

It's cut from 6061 aluminum and electropolished to a smooth, high-sheen finish, with the Bourne logo machined right into the top. Aluminum won't crack or go brittle the way an aging plastic cap can, so it holds up as well as it looks. It's a small part, but it's one of the most visible things in the engine bay, and a clean billet cap finishes off the top of the motor in a way the plastic original never will.

Fitment

Fits Honda and Acura engines that use the M33 x 3.5mm oil filler thread, which covers the vast majority of them, including the B, D, F, H, J, and K-series. If you want to be certain, pull your current cap and check the thread before ordering.