Should I Run A 10 Micron Or A 30 Micron Oil Filter? By S&S Cycle.

oilfilter“A micron rating is given to show the efficiency of the oil filter (one micron is a millionth of a meter). This leads consumers to believe that the 10 micron filter must be better for their bike. Here is where it can get confusing. Though the 10 micron filter may have a higher filtration rating it does not allow the oil to return to the tank as fast.

With this in mind, the 10 micron filter was developed for use with the Twin Cam style engine, which has a different oiling system that allows oil to be forced through a more restrictive oil filter. The reason for the tighter filtration was explained by the manufacture as necessary to assure all of the smaller passages, in the Twin Cam style engine, would stay clear of debris.

If you run the 10 micron filter with an evolution style engine it will not be able to return oil through the filter fast enough causing the oil to back up into the lower end robbing power and/or causing oil to puke out of the lower end. The 30 micron filter is designed to work best for your Evolution style engine, the filtration is still excellent and it will not cause oiling issues.

When it comes to filtering oil, application is very important. There have been a lot of changes and updates in the market with too many filter brands claiming a better filtration. Don’t be fooled into using a filter that might not be the best for your bike.”  S&S Cycle.

18 Responses to “Should I Run A 10 Micron Or A 30 Micron Oil Filter? By S&S Cycle.”

  1. 1 58_pan Sep 15th, 2016 at 10:24 am

    This applies especially to Sportster engines, they have an inherently weak oil pump and a 10 micron filter will cause top end oiling issues.

  2. 2 Zundap Sep 15th, 2016 at 11:46 am

    Always use the filter recommended by the manufacturer (OEM) before using any product from S&S.

  3. 3 Zundap Sep 15th, 2016 at 12:00 pm

    PS, I have been using a ten micron filter on my 1995 883 and 99 twin cam since new. Neither bike has ever had any mechanical issues or ever had an oil pressure light flicker even at idle on 95 deg. day. I recently called Fram oil filters with this same question before this article and they recommend the same filter for both engines. AGAIN, use the OEM filter.

  4. 4 Boomer Sep 16th, 2016 at 7:29 am

    I had a 2001 Dyna that ran great but at freeway speeds it would blow oil out the breather. I bet this was why even though it was a TC. It would sure be interesting to go back in time, change that oil filter, and see if it cleared the problem.

  5. 5 calif phil Sep 16th, 2016 at 7:46 am

    The S&S oil filters are my favorite. American made and very high quality.

  6. 6 Shanedrive Sep 16th, 2016 at 8:39 am

    Zundap- the correct OEM filter-as you state- for your XL IS a 30 micron filter, not the 10. The correct oem part number chrome is 63796-77A and black 63805-80A black. The fact you’ve never had an issue is not a surprise as many dealers just tell customers to use the twin cam filter in all applications (10 micron). Most don’t have a problem but the fact is, there will be and there is more oil in the engine causing drag as the article states when using a 10 micron on an engine designed for a 30 micron. No doubt the engine(s) will run “o.k.” but not optimal. Just sayin’.

    HD’s filters are made by Fram. SS’s filters are made by Wix. Both good brand names. I could ramble on about this subject. Been privy to witness testing on this subject.

  7. 7 MAGNET MAN Sep 16th, 2016 at 9:18 am

    Gentlemen, I manufacture Super magnetic oil plugs for most all applications. Customers give me my best advice. They recommended I carry K&P Engineering cleanable, reusable oil filters because it is so related to what we do, help extend the life of customers machines.
    Many people do not realize that the paper used in spin on oil filters is made in Romania and is layers glued together.
    I cut open a number of new filters and tried to blow air through the filter material with my mouth. NO GO! So what I was told was oil cannot get through the paper fast enough, if barely at all and the pressure builds up to where the by pass valve opens and is where most of the oil going to the engine comes from, the by pass valve…… unfiltered!

    The K&P filter on the other hand uses an aircraft grade 303 stainless steel mesh to always actually filter the oil and to flow up to seven times more oil if engine requires it. Eliminating oil pump head pressure which uses horsepower to create. K&P manufactures FAA approved oil filters here and in Europe.

    I use one on my Ford powered Land Rover and Honda Gold Wing Eurowing Trike.
    My first sale was a 2015 Dodge Hellcat to a gentleman named Ted from Wisconsin. Ted called to say “My Hellcat runs cooler and had increased oil pressure by 6psi and no lag in oil gauge movement at startup. Rich, I am a happy camper”. K&P Engineering oil filters are used extensively in Nascar and Formula 1 cars. They are made in the USA in Colorado. Say Richard from Dimple products sent me.

  8. 8 Zundap Sep 16th, 2016 at 9:26 am

    Shanedrive, very well said. Always use the oem or same part # after market filter on your engines.
    FYI only, I have drained the sump on another Sportster that has a sump plug immediately after riding over 100 mi. using a 10 and then a 30 micron filter. The oil was within 1 oz. with both filters. I have also done extensive testing on filters, oil pressure, and viscosity. For street application stick with oem parts.

  9. 9 richards Sep 16th, 2016 at 9:30 am

    Magnet Man…Can you tell us the filtering of the k&p reusable filters…are they 10 micron, 30 micron or “other”. The S&S article is about flow and filtering capability.

  10. 10 Craig Sep 16th, 2016 at 10:12 am

    35 microns

    Want to solve the oil blow back on Harleys, this is the answer. Fixed mine.

  11. 11 Mdkuder Sep 16th, 2016 at 12:52 pm

    While working for a filter company I found that the filter should be open at first and as the dirt particles load up the media they will make the filtration tighter and those ultra filters will load up quick and then the oil might just open up the bypass valve to keep the engine from being starved. But I’m just a drafter what do I know………

  12. 12 Zundap Sep 16th, 2016 at 7:28 pm

    Mdkuder, you are correct. The 10 micron filters are 10 microns at 50%.

  13. 13 SYF Sep 19th, 2016 at 9:24 am

    Oil does not flow through paper filters. It flows along the pleated paper, a common misconception.

    Not that K&S fiters are bad.

    They did copy Pure Power though. Check out Pure Power for any oil / oil filter related info.

  14. 14 boston jim Sep 19th, 2016 at 10:34 am

    Hey Guys, I’ve owned H-D since 1967 ! Been an AMSOIL Dealer since 2004, doing Bike shows up & down the East Coast for 10 years. I had a 1/2 dozen oil filters opened, the filtering material on display. Fram was the cheapest & the worst, H-D 10 micron Twin Cam filter had approx., 64 sq. in., while K&N (made in Thailand), had 164 sq. in., (very, very restrictive) was the most expensive, (must have been the Freight cost, from Asia)? I use AMSOIL, Abram Tank Technology Nano- Fiber Material, Oil Filters, in all my vehicles! I use a Evo Dyna 30 micron in my 1st year Evo Sportster, much longer. It won’t fit my 1999 FXSTC, last Evo Big Twin, because of the Stator Plug! My 1999 manual covers the last Evo Softail & the 1st year Twin Cam Touring Bikes, it does state, that you can use the 10 micron Twin Cam the Evo! I subscribe to a dozen M/C magazines, after reading several articles about the opposite oil directions of the Evo & TC motors, I began to wonder. Around 2003, H-D issued a Service Bulletin to Dealers, STOP using the 10 Micron Twin Cam oil filter in Evo motors, too restrictive!
    PS, For those that don’t know; The oil in an Evo motor is drawn by the 2 stage oil pump, from the oil tank, pushed thru the motor, into the oil filter, & back to the oil tank. This is where the 10 micron filter restricts the oil, backing up in the motor, puking out wherever it can. On the other hand, the more powerful TC oil pump, draws oil from the oil tank, pushs it thru the 10 micron oil filter, if you’re using a very restrictive K&N oil filter, you might be starving your motor of oil? Donny Peterson had a Great article in AIM, several years ago. He stated, that maybe the Evo 30 micron, might be a Better Choice for Twin Cam Bikes! Google Donny! He’s the MAN!

    PSS, One more point, the 10 micron H-D Twin Cam oil filter’s By-Pass Valve opened at 10 PSI, AMSOIL at 12 PSI, & K&N at 14 PSI? On paper, it looks like the K&N is the BEST, with the Most Filtering Material & the Highest PSI ! But, in the REAL World, I ‘d Bet the K&N, & the H-D oil By-Pass Valves are always open, allowing UNFILTERED oil to enter your motor? Check it out & Research !

    PSSS, There is NO governing body, group, etc., for oil filters! One companies 10 micron , is anothers 30 micron? Guys this is the Wild West, when it comes to Filtering Material, By-Pass Vales, Spring PSI’s, etc. ? Buyer Beware! I do like the concept, of the NEW motor! I wish H-D well! BJ

  15. 15 Zundap Sep 19th, 2016 at 2:07 pm

    boston jim, good stuff, thanks.

  16. 16 boston jim Sep 20th, 2016 at 7:10 am

    Hey Zundap, I had a Ice Racing Zundap in the late 60’s,early 70’s! Pretty Cool!
    Zundap, I wanted to mention, Harley’s are Dry Sump, you should NEVER pull the Casting Plug, It’s not suppose to come out, ? Now you have a dry motor, a void, you lost your oil pressure, after you fill the oil tank, you’ll have a dry start, it’s going to take awhile for oil to get to everywhere it needs to get to? A Good Tip, after you change the oil in a Sportster oil Tank, put the Bike on Kickstand, I use an Evo Dyna filter, it’s much longer, I 1/2 fill it with AMSOIL 20W-50, before screwing it on. I also use the Scavenger, to get that extra qt. of Dirty Oil out, without losing any oil pressure! fatzusadotcom, BJ

  17. 17 Zundap Sep 20th, 2016 at 9:40 am

    boston jim, I have a 100 cubic in S&S sportster motor that has a sump plug. The oil temp in the tank is 260deg. with 20/50 Amsoil and 250 with Valvoline VR1 20/50 or 30 wt. The sump retains 15oz’s when the oil is drained. I need to drain all the oil trying to figure out which oil will run coolest. When I drain the sump and refill the oil tank I let it sit at least overnight and let the oil in the tank sump out. The oil pressure light goes off immediately after start and no lifter noise. Next ride using Mobil 1 10/30. So far it runs best @ 245deg. on VR1 30 wt. for 50 miles then 250. The other oils run 250 after 25mi. The engine runs so hot I burnt my fingers on the gas shutoff valve and my feet get hot threw the rubber foot pegs and the soles of my boots.

  18. 18 boston jim Sep 22nd, 2016 at 8:32 am

    Hey Zundap, I always wanted a 100″ S&S motor for my 1986 1st year Evo Sportster! I envy you, you’re the man! I just wanted to mention, that Mobil is not as Good as it use to be, they have Cheapened themselves, they have been using Basestock 3 oil, Amsoil & Red Line are the only ones using Basestock 4 oils ! Thicker oils like 60W, are hard to cool, they retain Heat! I use AMSOIL 20W-50 in the motor, 10W-40 in the combo tranny/.primary, if it’s Good enough for a Hyabusa, it’s Good enough for my Old Sportster! Erik Buell was factory filling his Bikes with AMSOIL 15W-50 Dominator, a car racing oil, with lots of ZDDP, also has a Friction Modifier, Buell is looking for more HP. It can’t be used in the Primary, the clutches will slip! Are you running a Real Good Oil Cooler?
    PS, I find it amusing that S&S was giving out a gallon of 20W-50 Mobil V-Twin, with every motor they sold! Then recently they had Spectro make an S&S Brand Oil, that didn’t last long, not sure what they are doing now? When Spectro was making S&S oil, I thought to myself, is Spectro making Better Oil for S&S, than they make for themselves? I doubt it!
    PSS, Email me your address at, & I’ll send you 3 different oil study’s!
    Beware, Be Smart, Be Safe, Boston Jim
    PSSS, you really need to go to the Evo Dyna 30 micron oil filter, that 10 micron you’ve been using is restricting oil travel, keeping the oil HOT! Good Luck!

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Cyril Huze