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URGENT oil question, 10w30 - 10w40

Discussion in 'Maintenance and Servicing' started by Freeform, Dec 26, 2011.

  1. Hey guys,

    I'm riding a cb1100 (big air/oil cooled donk), about to jump on the ferry for tas however I noticed that the oil level indicator is riding on minimum.
    No stores in melb open today stock the 10w30 recommended in the manual.

    If I top it up with 10w40 will it damage the engine?
    Is it better to leave it and try my luck in tas?

    Let me know asap thanks :)
  2. I'll preface this with I am not an expert :) The numbers represent viscosity at cold and hot temperatures. So the 10W40 will be a little more slow to flow at cooler temps but work over to a higher overall temp. A top up should be fine if it is low enough to be dangerous. But best to use 10W30 if that's whats recommended in future. Have a good trip. :)
  3. Nearly^^^^ The 10w40 will actually be the same viscoscity at low temperatures, but act as a 40w instead of 30 at high temperatures. Should not cause any issues at all. I'm actually surprised that your big air cooled engine only needs 10w30 to be honest.

    PS I'm certainly no expert either, but would not think twice about doing it to my own bike.

    PPS Just had a look at the owners manual for your bike, and 10w40 is actually recommended for higher temperatures. Go for your life.
  4. 10w-30 and 10w-40 are just estimates. I remember from a test graph that 10w-40 are slightly thicker at low temps, but not enough to care.

    If you want to splash on cash, Id recommend 0w-40 synth, like Mobil 1.

    Youll cover both bases then.
  5. Why? 10w is good for -10 C. Where in Oz are you going to ride in colder temperatures than that? Unless you just want to throw money away. Who am I to stop you doing that?
  6. Its not just the lower temperature range, but that the viscosity is closer to the operating temperature range right from a cold start.

    Besides, what oil did you have in mind that doesnt classify as throwing away money?
  7. Being that the motor is air cooled, do not let the oil level continue to run on the lowish side.

    If you are not able to replenish with the specified oil grade than 10-40w will be ok.
  8. It wont harm anything except your fuel economy.

    I run 10w50 in a bike that recommends 10w40.
    In Aus summers (well like last years anyway) the bike was always over 100 deg C and the oil gets quite thin when its over normal operating temp of around 80 deg C. Bit of extra protection doesn't harm the engine.

    EDIT: unless its a non-motorcycle oil that includes additives not meant for wet clutches... [/disclaimer]
  9. Your thermostat opens around 85 deg C. Operating temp is around 100 deg c.
  10. yeah especially in an air-cooled bike I would use 10W-40 or 10W-50, just make sure as said above that it doesn't contain friction midifiers as they dont agree with wet clutches.

    It's also worth considering the tolerance levels of your bike/age as a thin 0W oil you'll likely get higher oil consumption...
  11. Agree with the others. 10 - 40 non friction modified will be fine.
  12. Both are tens and the same at start up.
    The forty will help at operating temps. Better than the thirty would.
    The English side of the manuals are written for the American market. Where the Av temp is about 5c below ours.
    10/50 with your tolerances might be too thin. Don't know though for sure.
    The castrol 10/40 synthetic at super
    Cheap is cheap and a good oil.
  13. Most owner's manuals show a you need to use different weight oils in different ambient temperatures, I am assuming that your manual says you should use 10-30 in Australian summer conditions.

    Am I the only one who thinks 30 sounds low?
  14. From memory 10w-30 starts to be too thin at 100 degrees C, 10w-40 at 120 C
  15. Agree with this. There are also a a few air cooled engines that will start to leak when 0W is used. It's not cold enough in Australia (even Tasmania!) to need that low a viscosity, and a couple of minutes of going easy on the throttle from start-up will easily manage the cold-start wear issues.
  16. No, particularly for a big air-cooler. Still, you'd hope that Honda know what they're doing............
  17. what? no! 10w is a standard developed by API for single weight oils, in multi grade it refered to how it flows like at "cold"...

    a 10w-40 flows like a 10w at 40C and flows like 40w at 100C. This range of temps is developed by API. The ACTUAL viscosity (measured in centi stokes) is determined by each oil - yes they vary, but the standard range for 10w-40, most common on bikes, is around 100cSt @ 40C and around 15cSt @ 100C (operating)

    how can you know what's too thin for a specific bike unless it's specc'd for much higher viscosity? all hot temps are measured at 100C, what varies is the kinetic viscosity....

    for example, a 10w-60 usually is around 150cSt cold and 25cSt hot... whereas the 10w-40 as above, 100 and 15 respectively... see how it's thinner across the range!! 10w is not a standard or what its good for at -10C or some other rubbish, it's based on an old guide developed in the 50s for single weight oils and is roughly translated to modern oils, for that actual viscosity, consult manufacturer info such as MSDS

    eg, http://www.amsoil.com/storefront/amo.aspx

    srsly, if you don't have a clue, don't comment.

    OP, you are free to mix 10w-30 and 10w-40, no issue and much better than running low - that's when real damage occurs. You can use any oil as long as it is JASO certified (i.e. good for motos) MA means no friction modifiers and MB is for motos that require modifier (rarer)...

    you can read all you want about oil here: http://www.ferrarichat.com/forum/faq.php?faq=haas_articles
  18. That's for a water cooled bike not oil air cooled.

    Tapatalking from somewhere, maybe even behind you so look out!!!
  19. I was not referring to a single weight oil. Rather, the choice of a 0W40 compared to a 10W30 or 40. With referance to the chart in the owners manual.
  20. a 0w-40 is still ~75cSt at cold, rather than the 15CSt it needs to be at operating temp. It's a race to operating temp with oils... all of them are way too thick at "cold" start up, remember, this is at 40C so not really cold at all, so the thinner the better if you do many cold starts...

    it gets a bit more complicated, and its a balancing act as with many things when you compare the superior film strength and sheer of thicker oils, or those with a closer weight range etc.