Gear Oil, Primary Fluid, Need Clarification

Discussion in 'General Harley Davidson Topic' started by franka, Dec 19, 2010.

  1. franka

    franka Active Member

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    Currently I run Castrol 20/50 in my oil bag, Spectro 6 in my tranny and HD Formula + in my primary. Question is I read on this forum about using Spectro for gear oil, when I think of gears, I think tranny?
    Question is what specifically are the posts referring to when they say "gear oil", tranny or primary?
     
  2. Hoople

    Hoople Account Removed

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    I have always looked at gear oil as being manual tranny oil and the primary oil as being a wet clutch oil.
     
  3. BUBBIE

    BUBBIE Well-Known Member

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    IMO, Gear Oil is for the tranny.

    I would not put gear oil in the primary.....(special oils not Gear Oils for that application) JMO

    Hd does recommend Formal + in the primary... I don't use it on TC's but Have in my sportster, In a sportster, F+ is what they recommend in the Transmission-Primary as They Share the Same Compartment.

    So Go figure

    signed....BUBBIE
     
  4. NEWHD74FAN

    NEWHD74FAN Experienced Member Retired Moderators

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    As Hoop says for Big Twins, but for Sportster where tranny, primary chain & clutch are in the same hole...a good gear oil...like GL-1 or Primary Gear oil safe for Wet Clutches specifically on the bottle (I use Formula+ for that reason and that friction modifiers are a no-no to wet clutches).:s
     
  5. Jack Klarich

    Jack Klarich Expert Member

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    All separate compartments on a Big Twin, I have always used gear oil in the tranny, call me old fashioned but IMO gear oil is just that meant for its high shear strength and bearing lube qualities, and for the primary I like H D formula+
     
  6. TQuentin1

    TQuentin1 Well-Known Member Staff Member Moderator

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    Your set up is great. Keep it that way, and you will have a very happy drive train!!

    TQ