Motorcycle Motor Oil ,specifically For Air Cooled Engines Vs. Regular Motor Oil

Posted in Crank, Oil and Piston

Is there a significant difference?
Harley, V-Twin, Separate gear and motor oil.

There are 11 Answers for "Motorcycle Motor Oil ,specifically For Air Cooled Engines Vs. Regular Motor Oil"

    1. robert p says:

      In the research I’ve done on this subject I’ve found the only “car” oils to avoid are the 5w-20, 5w-30, & 10w-30 oils. They have the star on the front of the container. Those oils contain “fuel saving friction modifiers that can cause clutch slippage. Most bikes call for 10w-40 so there usually isn’t a problem.
      I’ve used Castrol GTX 10w-40 and 20w50 in a Honda 300EX for years and not had any problems.The 300EX is an air cooled ATV and I’ve beat the heck out of mine and not had any clutch problems at all. I’ve talked to other people who have used other brands of “car” oils and not had problems. As with anything, keep the oil changed regularly.

    2. geo46er says:

      You could start a real heated discussion in this forum (or any other) asking questions like that. Ask ten different guys, get ten different answers. If you use the manufacturers recommended oil you can’t go wrong. JASO standard oils are currently recommended for bikes. Supposedly they contain detergent packages that resist the shearing action of the transmission gears, which in a car they are not subject to. Most riders change their oil way more frequently than they need to, so, does it make any difference? Maybe, if you keep and drive your bike for thousands and thousands of miles. If you have just purchased a new $18,000 Goldwing, put the good stuff in, protect your investment. If on the other hand you are driving an old POS 1980s something or other, put anything in it, it won’t make any difference.

    3. bluff_michael says:

      Mobil 1 motorcycle specific oil (made in UK) has the additives that have been removed from oil made in USA. The purpose of the additives is to carry off heat.

      Note that Harley-Davidson, at least used to recommend diesel crankcase oil in the event that Genuine H-D oil is unavailable.

    4. choppersr4riding says:

      Motorcycles have a motor and transmission sharing the same oil cars don’t. The motorcycle oil is made to meet the demands placed on it by the transmission and clutch. The motorcycle oil has more additives needed to prevent premature breakdown. The extra additives add to the cost of the oil. For more information visit ^(

    5. Tropical Weasel says:

      Pay no attention to the “Spectro Oil” salesman. Listen to the Guy who said Castrol 10w-40 or the 20w-50. Keep an eye on it and change often.

    6. gixx says:

      run the oil that’s right for the bike. 20w50 motorcycle oil

    7. tommy44432 says:

      Owner’s manual…read it.

    8. shovelkicker says:

      I have seen this thread on many a site. And yes there is a difference in the additives and the chemical make up.

      Basically the problem with Harleys (I own 2 currently) is that they are air cooled.
      The higher temps break down the oil to fast and I don’t plan on going into the chemical analysis here. But that is why HD says in a pinch use oil rated for diesel engines. For a long time HD used to say that synthetic oil was bad, and many of us used “Mobil 1″ 20w50 with no problems.
      A few years ago HD began buying “Mobil 1″ 20W50 and selling it as Screaming Eagle V-twin synth oil. Mobil also began selling 20W50 V-Twin Air cooled oil.
      “Mobil 1″ is the easiest oil to get your hands on that will work in air cooled and diesel engines.
      AmsOil is also a great oil to use if you can get it, but use their V-twin oil. Amsoil did a study on motorcycle oils ^( which if you read it, you will see that it is not bias.

      Other motorcycles have the problem of sharing oils, like the sporster and other sport bikes. So using car oils is also not good.

      If you are in a pinch and need oil, it would be better to run a 20W50 car oil then no or really low oil. But get it changed out as soon as practicle.

      Clear now?

    9. 51 says:


    10. Mad Scientist Matt says:

      I’ve seen a few reports when people tried to subject those claims of motorcycle oil’s anti-breakdown additives to controlled tests. The result? No real difference; they both seemed to break down at about the same rate.

      There is one thing to watch out for, however. The thinner automotive oils, especially the ones marked Energy Conserving, have additives that make a motorcycle clutch slip. However, the thicker automotive (or better yet, diesel truck) oils don’t seem to be a problem. I’ve seen a lot of debates over which oil to use on a bike, but I’ve never, in any of these debates, seen anyone actually report they’d damaged their bike by running the right weight automotive oil in it.

    11. tree8588 says:

      The major thing to stay away from is in the API code ring on the back and is the “Energy Conserving” oil. This has teflon in the mix and will cause your clutch (if it’s wet) to slip. 20W50 is a good mix and go with the synthetic stuff, just lasts longer and doesn’t break down as fast.

      I use Castrol SynTec 20W50 with no problems