Oil recommendations for high mileage evo

Discussion in 'Oil' started by mr monk, Aug 27, 2013.

  1. mr monk

    mr monk New Member

    Just picked up a 94 Fat boy with 75,000 miles yes 75k. Runs well. Do not have any history on bike as far as what fluids were used where. The bike sits for a few weeks starts up quiet, no smoke and the tranny and clutch work excellent.

    I am draining an ounce or two out of each and found one trick to determine if it is fossil or synthetic by putting the cup of fluid on ice and seeing if it gets thick. If it does it is fossil. Any other tricks?

    Here is what I have done so far.
    1. Primary removed 1.5 ozs of fluid. As far as smell goes it smells like true differential oil, like that from the rear of a 1970's car. Should I assume that it is fossil?
    2. Engine oil has a pretty strong smell of gas so I am not sure if the ice trick will work.

    So I guess the big questions are any tricks to determine if current fluids are synthetic or fossil, and what type and what weights I should reinstall. I also live in South Florida.

    Thanks for the input.

  2. lorne

    lorne Senior Member

    welcome to the forum...i wish i could be of more help with the fluids but there are better minds than me that will be along to help you out.

    i just wanted to say that you can still get alot more miles out of that old EVO. i believe Don got 165k plus out of his 96.

    BUBBIE Well-Known Member


    Send EACH out for/to a Oil Analyst... They would tell you up front on the phone IF they could determine the oil being synthetic or fossil. Probably not the Brand.

    I have Never done this but it sounds REASONABLE to my thinking.

    Others will probably chime in here and agree OR answer you differently.

    Either way you go, being it doesn't use oil.

    I'd probably use a 20/50 synthetic (Redline, Mobil1, Spectro)
    HD Formula + in the primary. OR MTL by Redline
    A Gear Oil in the tranny (shockproof by Redline)


    THANKS lorne,,,,,Hope that is me...........:)
  4. lorne

    lorne Senior Member


    see there is a better mind..:s
  5. STEVE07

    STEVE07 Well-Known Member Staff Member Super Moderators

    I would just go with a good quality dino oil in the EVO.
    I run synthetics in my twin cam, but my 93 evo is just fine with dino oils.
  6. HDDon

    HDDon Experienced Member Contributor Retired Moderators

    I put 62,000mi on my 94 EVO before I did a top end job. And put another 74,000mi before I sent it off to the reman. program at HD. I have to agree with Steve that a good dino oil for the motor and HD primary fluid. I have run Spectro and Amsoil severe gear lube in the tranny with good results. I would be a little worried about the gas smell in the motor oil, you probably have some worn rings and I would be thinking about doing a leak down test at the least. With 70,000+mi. a good top end job with all the new gaskets are something you need to think about.
  7. Jack Klarich

    Jack Klarich Expert Member

    Welcome to The Forum, I would run a compression test first, if it comes back good you could run a dino oil of your choice, in South Florida with hot ambient temps you could run a 50 weight, tho it may start a bit harder on cooler mornings
  8. tourbox

    tourbox Senior Member

    Welcome to the forum from So. Texas. I agree about the Dino juice for the motor. I ran Valvoline Racing oil in my '96 UC and had close to 108K on it when I sold it. I don't think your pet-cock is vacuum operated so previous owner may of been in the habit of leaving it turned on. Possibly seepage thru the valve or carb. caused your smell of gas in the oil. It's best to turn off the valve when stopped/shut off for a while. Old school theory. Just monitor it a while and then do the other suggestions for peace of mind or need be.
  9. Jack Klarich

    Jack Klarich Expert Member

    Me thinks 94 was first production use of vacuum pet cock in big Twins, check for vacuum hose to pet cock, these were notorious for leaky diaphragms:s