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  1. turbofiat124

    turbofiat124 Premium Member Forum Donor

    Wonder what's the difference between 2 cycle oil and non detergent SAE-30 crankcase oil? Years ago before "2 cycle" oil was available, SAE-30 crankcase oil was what was mixed with the fuel.

    So what's the difference? Is the actual 2 cycle oil less likely to separate from the fuel over time?

    The Lucas semi-synthetic oil I've been using is a 20 weight. The Opti-2 which I have used in the past is a 100:1 mix and is the equivilant to a 40 to 50 weight crankcase oil.
  2. Wartburg353W

    Wartburg353W Loyal Comrade

    I think the main difference is how cleanly it burns. The Wikipedia entry says 2 stroke oil has a lower ash content and leaves less deposits as it burns. Any issues of differences in weight or such among various 2 stroke oils would go to what sort of engine/oiling system they are intended for. Pre-oiling system, outboard, yadda yadda.
  3. Keri

    Keri Leader

    seems to me the oil question has been bounced around a whole lot already…

    Yes, many years ago, one mixed plain oil with gas for 2-cycle motors.
    Usually at something like a 16:1 ratio, or 6.3% which is a whole lot of oil.
    This massive amount of oil ensured lubrication, but caused massive amounts of deposit build-up and massive amounts of smoke, as well.
    If the pistons rings stick from deposit build-up, no amount of oil will save the pistons and bores.

    The synthetic, or more honestly, "semi-synthetic" oils burn cleaner, reducing build-up and extending intervals between "decarbonizing". In addition, they can provide better lubrication.
    Oils specifically formulated for Air-Colled 2-cycle motors (rated TC) also are intended to reduce piston ring sticking.

    A note on the "thin" 2-cycle oils… It is particularly important to never "lug" the motor at low RPM and high load.
    This is a really bad practice on any engine, but especially so on one with zero oil pressure, and 2% oil to fuel.
    The "thin" Semi-synthetic oil I've been using for the past 50,000km works well for me, but I am very conscientious about keeping the engine turning FAST ENOUGH to prevent "lugging".
    That is to say, I never apply heavy load to the motor at speeds under 3,000 rpm.
    This gives some observers the impression that I "race" the motor unnecessarily, but the high-quality semi-synthetic can handle high RPM lubrication.
    This topic also has been posted previously.

    If one is intent upon running the motor at low RPM and full throttle, a heavier oil at higher percentage will slow down the inevitable damage to the crank, if not the rings.
    Andrew likes this.

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