Robin Subaru EH035 - What oil to use ???

Discussion in '4-Stroke Motorized Bicycle Engines' started by ballermj23, May 29, 2011.

  1. ballermj23

    ballermj23 New Member

    What oil is recommended for this engine.:confused:

    this is what i have found at robin america website.

    Engine Oil SAE 10W-30 SF or higher

    well whats best for my little engine.:cool:
     
  2. lowracer

    lowracer Member

    ballermj23,
    I have an EH035 & run 10W-30 regular dinosaur oil & have thousands of trouble free miles on it.
    The owners manual has single grade recommendations anywhere from 5W for -4 F up to 40W for 104 F.
    Also multigrade recommendations of 10W-30 from 0 to 90 F
    & 10W-40 from 0 to 120 F.
    Hope that helps...
    -Lowracer-
     
  3. ballermj23

    ballermj23 New Member

    thanks im going to buy

    Mobil/1 qt. SAE 10W-30 full synthetic motor oil

    at autozone
     
  4. lowracer

    lowracer Member

    Let me know how synthetic works out for you.
    I change my oil often & have never tried synthetics.
    The EH035 holds very little oil, so a quart lasts a long time.
    -Lowracer-
     
  5. loquin

    loquin Active Member

    I would run regular oil during the break-in period. Then, flush it, and replace with the synthetic.
     
  6. sparky

    sparky Active Member

    I'm just coming to ask this question myself.

    I just want to know what exactly is "better than SF-rated" oil??

    From what I'm found, it seems that dino oil is good for several thousands of miles. So I'm not going to doubt that.

    I have also read that there is no benefit to synthetics until AFTER 3,000 miles in a car. So that's at least 50-60 hours right there.

    I would concur that there is likely no benefit to synthetics.

    If it's getting to 100 deg temps, tho... should I go with 10-40 or 20-40?? :devilish:
     
  7. HeadSmess

    HeadSmess Well-Known Member

    the lower number is for how cold it gets...

    if you get -10 mornings then maybe using a 0/10 even...

    thats basically it. thinner is better in a pipsqueak like this where the ease of ditributing all 75mls or so of it makes a big difference... and lower numbers equal thinner oils.

    the higher number should be the maximum ambient temperature... so i have to go with 50 in summer :)

    synth versus mineral. theyre basically the same. made from the same stuff.
    mineral oil is distilled from goop from the ground, then has all the smaller molecules boiled out of it.
    synthetic is the stuff that was boiled off stuck together again in a well controlled manner, hence the price.

    i believe synthetic tends to break down at extremely high temperatures.

    but then, they rave on about it and charge for it like its gold, so it must do something...

    me, im cheap and stick to nice 10/40 mineral :) changed so often its silly... 4l is cheap.
     
  8. sparky

    sparky Active Member

    Yup, I'm sticking with 10-40 the whole time.

    Anything else was just silly.
     
  9. loquin

    loquin Active Member

    Regular oil tends to break down more than synthetic oil at high temps.

    The main difference between the two is that the (so-called) synthetic oil has a much narrower distribution of hydrocarbon chain lengths.

    here's an example to show what I mean by this - two sets of 10 numbers, both of which which average 5. Let's assume that the number represents the length (and therefore the molecular weight) of the hydrocarbon chains in oil.

    Code:
    5 4 5 5 4 5 6 5 5 6 : average = [B]5[/B]
    
    6 3 5 7 4 3 4 7 6 5 : average = [B]5[/B]
    So, if we think of these two sets of numbers as two types of oil, the first set would be analogous to synthetic oil, and the second set is analogous to standard oil. Both have the same average 'weight', but the standard oil has more variation of oil 'weights.'

    The second key point is this - all other things being equal, when heated, smaller, lighter liquid molecules are more easily turned into vapor than are heavier molecules. (i.e. - less energy is needed to 'kick them out' of the liquid.) Conversely, the heavier the molecule, the more energy needed to 'kick it out.'

    This means that, as your engine runs, and the oil heats up, the lighter molecules tend to 'evaporate' first.

    To apply this effect to our 'oil' number sets, if we remove all numbers (molecules) less than three, and half of the 4's from the number sets, we end up with:

    Code:
    5 4 5 5 [COLOR="White"]4[/COLOR] 5 6 5 5 6 : average = [B]5.111[/B]
    
    6 [COLOR="White"]3[/COLOR] 5 7 [COLOR="White"]4[/COLOR] [COLOR="White"]3[/COLOR] 4 7 6 5 : average = [B]5.71[/B]
    Since the lighter components of standard oil tend to get boiled away preferentially, what is left behind is, on average, the heavier molecules, and the oil is therefore 'thicker' than it was originally. This, of course, will lead to greater cold engine wear.

    With 'synthetic' oil, since there is a much lower number of 'light' and 'heavy' hydrocarbon chains in the mix, you don't get nearly as much 'thickening' of the oil over time. Sure, some of the 'synthetic' molecules get boiled away, but, since the molecules are much more likely to be nearly the same length, the oil viscosity doesn't change nearly as much.
     
    Last edited: Jun 15, 2011
  10. sparky

    sparky Active Member

    I think that answers the question as to why most people's cars start leaking after switching to synthetics!!

    After switching, the older mineral oil will gradually "fade" away, unclogging any leaks in the gaskets. Then the synthetic will just slip on thru.

    My uncle said it happened to him and was sure there was some correlation, and this is probly it.
     
  11. rawly old

    rawly old Member

    The thing is, it takes so little oil to fill a four stroke, i don't see how
    one can afford not to use a good synthetic. they're slipperier, can handle
    higher temperatures, and they don't break down!
     
  12. Old Bob

    Old Bob Member

    They do break down actually.and get loaded with contaminants just the same as dino oil.Which is why it needs to be changed.You don't save much or gain any power in these small engines with synth, you do save a little real oil but using synth dduring break in will prevent proper break in.
     
  13. rawly old

    rawly old Member

    okay, i'll rephrase my remark. they take a lot longer to break down.
    as for changing oil, i did it twice as often as recommend during
    breakin, and my engine gained power every time i took it out.
     
    Last edited: Oct 29, 2011
  14. Old Bob

    Old Bob Member

    The big thing is to change it often, the check balls in the R/S oil system like to build sludge and varnish, if they stick open kiss the engine goodbye.
     
  15. PatrickW

    PatrickW Staff Member

    Lou...you are a born guru and excellent teacher. I wish we could sit down for a few hours and just talk...I think I could learn so much. BTW, the R/S EH035 takes Less than 4 oz. (3.7 to be exact)...I Carry an extra 'squeeze bottle w/plastic neck' that holds 8 oz. of 10w30, and change the oil every month...it is very cheap insurance.
     
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