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Thread: Best oil choice for a 47EL

  1. #1

    Best oil choice for a 47EL

    To the point where I need some fluids for my 47EL project. What weight oil and brand is the best choice for this bike? Also what weight is the go to for the transmission?

  2. #2

    Re: Best oil choice for a 47EL

    Buy a case of 60 wt from your local dealer.
    Engine and tranny use 60 wt.

  3. #3

    Re: Best oil choice for a 47EL

    I've bought only 60 weight factory oil since the 70s...

  4. Re: Best oil choice for a 47EL

    I use Castrol "classic" 50 straight for engine and tranny.

  5. Re: Best oil choice for a 47EL

    I use BelRay brand in the transmission, its red so easier to distinguish between transmission and engine oil drips.

  6. #6
    Join Date
    Aug 2010
    Twin Cities, MN

    Re: Best oil choice for a 47EL

    I use straight weight mostly from Harley-Davidson. Specrto oil isn’t easy to get around here. But then again it’s not really needed. But I also use 50 weight in the spring if I want to ride, until about June 1. Then dump it and run 60 weight until fall. Then dump it so I have fresh 50 weight for the spring again.
    1947 EL
    1948 FL Project
    1947WL Project

    But there's booze in the blender
    And soon it will render
    That frozen concoction that helps me hang on

    You never get just get less awful. "Joe Walsh"

  7. Re: Best oil choice for a 47EL

    Howdy sir,

    More important than brand or viscosity is what’s in it or in our case, not and much needed and that would be ZDDP to protect against sheer/scuffing effecting flat tappet motors and the valve train. Though OHV motors of this vintage primarily did not have as large and heavy valves as flatheads (Heavy to survive the extreme heat and big because of poor flow) they did/do run rather high valve spring rates compared to any modern motor designed to run without ZDDP additives and with lighter valves and spring pressures.

    The last generally available purpose oriented oil containing this was Diesel Shell Rotella, but alas, no more. But, there is a reasonably priced readily available oil containing this additive. Valvoline VR1 20-50 racing oil. For off-road use - ZDDP removed because of harm to catalytic converters - it specifically states on the bottle “high zinc formula also protects push rod and flat tappet engines” .....also mentions that cat converter thing.

    Going with 75 year old oil viscosity recommendations is about as valid as adhering to period tire pressures with now completely dissimilar rubber hysteresis. Air cooled engines have heat concentration points that non-turbo’d water cooled motors in the main do not. This quickly broke down 60 wt oils back in the day. I’ll take cold flow and more rapid oil exchange through the system that modern multiweights provide.

    On a similar note and extension of the above on tappet protection, no engine oil can provide the sheer resistance of a real hypoid/trans intended lube, I run a GL 4 - 5 75-90W in all my HD’s and Indian twins.

  8. #8

    Re: Best oil choice for a 47EL

    So Peter are you say Shell Rotella Diesel is no longer available or that it no longer has ZDDP? I run it in my F-350 diesel pick up and get it at Walmart all the time or at least up until about 6 months ago when I last bought some. Inquiring minds want to know.


  9. Re: Best oil choice for a 47EL

    Howdy Rollo,

    Shell Rotello is as available as it ever has been, ZDDP and related sheer additives were eventually reduced below the stated threshold for flat tappet motors where they would be beneficial.

  10. #10

    Re: Best oil choice for a 47EL

    10-4 Peter See you in Fla?


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