Engine oil weight question

Discussion in 'Oil' started by Markk9, Jun 23, 2011.

  1. Markk9

    Markk9 Member

    I'm not trying to start a (EDIT) contest...................

    Why is 10-40 only ok when the starting temp is below 40? I understand the 10 weight oil flows better at lower temps, but with synthetic does it matter? How much better does a 10 weight synthetic oil flow compared to 20 weight synthetic? Once the engine is warmed up to operating temp and running on the highway, does 10-40 offer less protection then a 20-50? I would like to know, I'm a 365 rider, as long as there is no snow or ice on the road I ride to work. Winter time morning temps can be down in the upper teens and low 20's.

    On my non H-D bikes I run a motor cycle rated synthetic oil 5w-40. Would this oil cause problems to a V-Rod's engine if used during the summer?

    Please read and understand the info in this link...
    A Friendly Reminder - Harley Davidson Community
    Last edited by a moderator: Jun 23, 2011
  2. Slo-Ryd

    Slo-Ryd Junior Member Contributor

    This page should hopefully answer most of your questions.
    All About Motor Oil

    As for running the 5w-40 in your V-Rod, I can't offer my opinion as I just don't know. I would get that info from your local HD dealer to be absolutely sure whether ut's ok or not:s
  3. Dark Ker

    Dark Ker Member

    No, It won't cause engine problems. Does it provide less protection? Honestly, probably more protection than the heavy weight due to start-up; and the fact that because almost no one uses 20W-50, there isn't much working being done on the oil... leading into the next issue.....
    Remember the underlying "issue" with oils in motorcycles, is NO ONE specs for them.
    What I mean, is the SH, CG, etc ratings. The often referenced ratings(such as my dyna manual)that are spec'd are AT LEAST 15, and I think they are 20 years old. API lists them as obsolete. Nobody is doing engine sequencings, or standardized wear testing, for motorcycles. The SG/SH "motorcycle" ratings are automobile specs, NOT motorcycle.
    The closest to come to it was the Japanese with their JASO ratings. So as far as oil "rated" for your engine, none truly are.
    I have almost 12,000 on my WG, and I run Rotella 5W-40 T6. I have no issues
  4. cycleman11

    cycleman11 Member

    Go to the - Bob the Oil Guy site - on the web. All the info you'll ever want to know about oil and then some.