• Protip: Profile posts are public! Use Conversations to message other members privately. Everyone can see the content of a profile post.

Oil and Rad caps

28 November 2009
Are all Honda Oil and Rad caps the same?

I check my oil and water every time before i take my car out, I also get the oil changed on a regular basis perhaps 2-4 times a year.

My car is pretty good, i hardly ever need to top anything up but i check just to make sure, but when i do have to check the plastic oil cap is a bum to remove! i don't over tighten it either.

So i was looking at alternative oil caps which may make life a little easier. and because i was doing oil cap might as well get a matching rad cap. (expansion bottle cap)

Do all Honda Rad and Oil caps fit the Nsx?

I have been looking at the Mugen ones. Maybe Spoon, Mugen is more JDM surely?! haha.

Another Question...

While i was looking at oil caps i found something called Mugen Engine Treatment Oil MT105.

What is all that about? never thought there was such a thing, additive to the oil. More curious than anything, no intentions in running it.


"Mugen MT105 engine treatment is one of the most advanced additives that actually work! Used exclusively by Mugen for years, it is now available to you. Mugen MT105 prevents mechanical loss of engine power and reduces mechanical noise, improves fuel economy, and protects your engine of wear as well as improvement of its durability.

Even with racing engines built with highly precise components, moving parts such as valves and pistons cannot escape from friction loss. Molybdenum, which is a major ingredient of MT105, quickly penetrates into the metal friction surface. This makes a smooth metal surface by forming a strong lubricating layer, which in turn reduces friction resistance and minimizes loss of engine power. By holding the increase of metal surface friction temperature it stabilizes oil temperature, reduces metal friction noise, and improves engine durability.

The recommended quantity of MT105 to be added is 3% to 5% (or 30ml to 50ml per litre) of the engine oil capacity. Please add MT105 by using the attached measurement cup. Since this product is composed of high density organic molybdenum, too much quantity may have adverse affect on such materials as engine sealers."
I know the oil filler cap is interchangeable with Integras, since I got an aftermarket one. They may not be exactly the same - maybe they say different things or have a different shaped grip - but they're definitely interchangeable.
Most aftermarket oil caps are CNC and metal. So, they will be VERY hot to the touch vs. the plastic OEM cap. I'd suggest leaving the cap you have now unless you want to burn $100 on a fanboy oil cap that has no benefit.

It's not really a bling thing, it's more that the plastic cap is a nightmare to grip and undo. Not saying it will be any better for being metal however the design may be better.
Mine never seems to be an issue? I only take it off when the engine is cold and I'm changing the oil. Otherwise, it's always on.
Civic, Integra, Accord, S2000, NSX, and most other Honda oil caps are compatible. If you search you can find a Honda OEM jdm oil cap that is made from the oem plastic material but has a metal outer skin.

I once had a spoon oil cap (real, not a knock-off) that would not thread even close to all the way into my S2000 valve cover...really wierd. The further in I tried to screw it, the tighter it got. I had another S2000 valve cover sitting around and it woud screw into that one all the way with no problem. My OEM cap would screw smoothly into either valve cover. So maybe billet caps aren't that great an idea.

As to Honda coolant tank radiator cap...they are pretty much all compatible for fit but may differ as far as the pressure they will hold before releasing coolant out the overflow. I think Mugen and Spoon caps are designed to hold more pressure than stock which means they can handle higher coolant temperatures. Again that may or may not be a good idea for street applications.
Last edited: