I have an old Honda n600 from the 70s, but no one makes a filter for it anymore. The word from the n600 forums is that if you want a new filter you have to use one meant for a Honda motorcycle that's about 5mm shorter than the original. The n600 basically has a motorcycle engine, so that's fine, but it being short has me worried. Is there a way I can clean the old filter in my car now and re-use it? If so, how?

[And no, before you ask, there are no obscure dealers who still have OEM ones in stock according to the word from the forums]

  • 1
    You can find them....ebay.com/itm/…
    – Moab
    Commented May 16, 2018 at 20:13
  • 1
    If it were me I would use the new shorter ones and change them a little more often. Commented May 17, 2018 at 15:38
  • Dang, that's the first one to show up on eBay since I bought my car 2 years ago. Thanks.
    – Evans
    Commented May 19, 2018 at 12:16
  • What was the old filter number?
    – mongo
    Commented Dec 11, 2018 at 23:22

3 Answers 3


Practically speaking, cleaning a filter is impractical. The filter absorbs particles, generally to about 10 microns, which become embedded into the media. Even if one could "wash" it, much of the particulates would remain embedded into the media. (The media actually filters finer as it loads up.)

In addition to a slightly smaller filter, I would suggest that you investigate whether you could find an adapter to mate the existing filter mount point on the car, to an alternate filter.

In absence of that, you could eliminate the filter in the car, and using an adapter made from an old filter, route the oil to and from an separate filter. This has been done in several applications, and I have seen someone with this arrangement on VW diesel engines.

If the engine was ever used in marine applications there may be a similar arrangement for it, allowing for a remote mount of the oil filter.

Practically, you would be well served to make friends with a fab guy.

You should also scour filter catalogs, and determine the thread pitch, diameters of the gaskets, etc. Also consider bypass pressures if your original filter as a bypass valve in it. Then I would search the catalogs looking for a similar mating thread / diameter / gasket as well as bypass pressure, and look for a filter that will fit. It might be longer, or possibly shorter. It might be listed for lawn equipment or portable power equipment.

Otherwise that fab guy's creativity will be your friend.

In the end, a 5mm smaller canister will likely have no measurable impact.

Addendum: I just saw an aux filter added to a tractor, which had used a "toilet paper filter" probably from the 1930s or 1940s. The auxiliary filter adapted to the previous filter, and allowed, in this case, a large filter, that is commonly available. I don't have a vendor and part number, but the owner said it was easy to find from their ag and fleet dealer.


If the filter fits, but is only 5mm shorter in length, you are better off using that than trying to clean the old filter.

Reason being, the filter is what catches all the contaminates. In 5mm you will not lose that much filter area.


'Cleaning' a filter is NOT possible, as others already have mentioned. Microscopically small particles are stuck in it, and will never come out. Those make the flow capacity and filtering quality of the filter bad. All other options I can think of have better results than reusing a filter.

If the shorter filter fits properly, and doesn't make the oil bypass it, I wouldn't bother a bit with such a little difference. The oil(and filters) nowadays are orders of magnitude better than back in the 70s, so your engine is spoiled already regarding lubrication.

I personally like the adapter kits so you can use the standard spin-on filters nearly all cars use nowadays. They're easily obtained at a low price, while the quality is fine. You can pick one with a one way valve so it keeps being filled with oil, so there's no short period of no-oil pressure at start up.

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