primary fluid confusion?

Discussion in 'Softail Models' started by 09 deluxe, Jan 3, 2010.

  1. 09 deluxe

    09 deluxe Member

    I have read alot of different stuff on primary fluids and I'm a little confused.
    I have read that some people use 10w40, others, a straight weight like Spectro Primary which lists as straight 85. I'm not sure what is best? What weight is HD formula+?
  2. ooheritage

    ooheritage Active Member

    thanks smitty great down to earth explanation, hope you had a great holiday.
  3. Iceman24

    Iceman24 Well-Known Member

    09 deluxe; first - you don't want to use engine oil (10/40), or Synthetic in the Primary. I'd use HD Formula+, or go with Spectro Primary. From what I've found, HD Formula+ viscosity of 89/90 GO & 20/50 engine oil (combo) - specifically blended to work in primary case.
  4. barnak

    barnak Member

    Got Aimsoil 20-50 and work just fine.
  5. glider

    glider Veteran Member

    Synthetic oil in the primary in not only overkill but not the best choice because of it's excellent lubrication properties over dino oil, give this some thought before using synthetic oils in the primary and the effects it can have on clutch plates. I would never run syn oil in the primary myself.
    You don't want synthetic oil in the primary and as far as the newer bikes being different, please show me where they are different than the older ones in this area that brings you to this conclusion.
  6. glider

    glider Veteran Member


    The fact that some are using synthetic oil in the primary does little to validate it's application in the primary. Just like the people that use ATF in the primary, it wasn't made for it but it's used by some stating "I have never had a problem using it" which IMO is about the poorest validation anyone can give for a product This in itself means little when vegetable oil would work in the primary, just not as well as a product that is made for that area.

    People seem to think because they have 20-30---- K miles on a product and nuts and bolts haven't gone flying yet that it is OK to use in this area and this corroborates the fact. Use what is supposed to be used in a compartment and forget the substitutes unless you have deep pockets for repairs down the road.

    Also do some concrete research on something like this and come up with the valid facts instead of "it works for me"
  7. Jack Klarich

    Jack Klarich Expert Member

    I couldnt agree more, vegetable oil can be substituted for brake fluid in a bind but its main function is cooking and i aint cooking my brake pads LOL good to see u up Glider
  8. geezer

    geezer Senior Member Contributor

    I have to agree with Glider, works for me doesn't mean much to me if guys are trading every couple of years. Almost any oil will keep things turning for short time. I, however plan to keep my bike for a long time and many miles. The dealer told me just to use Syn3 in all 3 holes. I've owned enough trucks, tractors, combines and vehicles to know there is good, better and best. I wouldn't think of putting gear lube in a motor so why would I put motor oil in a gear box? Totally different types of lubrication are needed for each. Synthetic oil is much slippery so I wouldn't want it on a wet clutch.
  9. glider

    glider Veteran Member

    The dealer will push the Syn 3 in all three holes because there is a good profit margin in it for them. The smart ones however will carry a trans oil line like Spectro or redline and advise you that this is a good choice for the trans. They are the ones that are a cut above the ones recommending the Syn 3 in all three.
  10. Drumrguy

    Drumrguy Account Removed

    Gotta agree with Glider, no synthetic in the primary.