Primary oil for '99 Fat Boy......

Discussion in 'Softail Models' started by Detained, Aug 7, 2010.

  1. Detained

    Detained Member

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    Ok let's start with I HATE BUYING STUFF THAT SAYS H-D on it for my bike....
    That being said, I've been running 80-90 weight gear oil in my primary at first because I had a bad leak while on a 1600 mile trip then after I fixed the leak I saw no reason to change....... Basically I'm looking for some thoughts about this as far as what damage if any could possibly come from doing this.......


    Thanks!! :cheers
     
  2. glider

    glider Veteran Member

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    Considering the Formula+ is basically a 50 wt oil, the 90 wt you are using is a bit thicker and may cause problems when used in the primary such as clutch drag and hard shifting.

    Engine vs Gear Oil - Harley Davidson Community
     
  3. Detained

    Detained Member

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    Thanks for your quick reply Glider...... I guess I wanted to be sure that my newfound no charging problem wasn't somehow gonna fall back on what oil I used in my primary. I've tested as well as I can by using my H-D manual and pretty much the instructions on this site are basically the same, I had no light at the regulator prongs when using my test light and I unfortunately saw no VAC when using my multimeter at the outlet plug for the stator so I'll assume my stator took a dump on me so I'll replace it as soon as the money tree is ripe........
     
  4. glider

    glider Veteran Member

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    I think I would stay away from the gear oil in the primary myself.

    Most any dino oil will do the job in there like 10-40 or 20-50 but without friction modifiers.
     
  5. wlbowers

    wlbowers Member

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    Glider you beat me to it.

    No Friction Modifiers!

    I run Mobile synthetic 75/90. But I live in Memphis area. Summer here is brutal.
     
  6. Hoople

    Hoople Account Removed

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    Let me guess. I bet when your bike is stone cold and you drop it in 1st, it bangs.
     
  7. Detained

    Detained Member

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    My bike has gone into 1st a little hard on a cold morning but like wlbowers I also live in a very warm climate, Georgia and Florida along with my place in Pennsylvania, and the only time I really notice the bang is while I'm up here in PA. I never noticed any clutch drag or hard shifting at this point.

    I'll assume the "No Friction Modifiers" comment is for the clutch pack so I guess when I put the new stator in I'll consider the Mobile synthetic 75/90 as an alternative.....

    Thanks for your input guys!!

    Rick
     
  8. glider

    glider Veteran Member

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    The synthetics aren't the best way to go in the primary either. They can cause slippage in the clutch when you get a few miles on them over a dino oil in the primary.
     
  9. Detained

    Detained Member

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    All right Glider, out of curiosity what do you use in your primary? I've apparently been doing wrong with the 80/90 so now you have me at a point in my mind where I should just use what I use in EVERY engine I have, Castrol 20/50.... Every bike I presently own from my '69 Triumph, '76 AMF Sportster, my custom and the '99 Fat Boy ALL run Castrol 20/50 bike oil and every vehicle I have uses Castrol 20/50 including my riding mower. I've used this brand oil since I was a youngster with no complaints, the '76 AMF was my first American bike and I still own her. She tought me how to wrench on a bike, LoL......... :cheers
    Sorry to be beating this dead horse so severely, but I am always open to opinions with good reasoning behind them.

    Rick
     
  10. Jack Klarich

    Jack Klarich Expert Member

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    Is this motorcycle oil or car oil, big changes in the additive packages:s