Re: Two Cycle Oil
Most 2-stroke outboards require an ashless detergent oil because their ring-land temperatures run cooler. These are the TC-W3 oils. The ashless detergents work well in liquid cooled 2-strokes, like outboards, because the excess cooling usually holds the ring-land temperatures below 300F. Ashless detergents are manufactured form organic nitrogen compounds, like Hydrazine, instead of heavy metal compounds (like ash containing oil), so they produce no ash as they are burned away.<br /><br />Air-cooled 2-strokes require a low ash detergent oil because their ring-land temperatures can exceed 300F. These are your API-TC, JASCO FC and ISO GC certified 2-stroke oils. At higher ring-land temperatures the low ash detergents can keep the deposits to a minimum, mainly because these detergents are manufactured from compounds of Calcium Phenate and Magnesium Phenate which burn away, but form a heavy metal salt ash that's expelled during normal combustion. Ash type detergents depend on the higher combustion temperatures to keep the resulting ash swept out.<br /><br />Ashless oil meeting TCW3 specs only will not protect an engine requiring low ash API-TC, etc. type oil. The opposite is also true. Using a low ash oil in an engine designed for an ashless type oil can result in fouled plugs and gummy combustion chambers. <br /><br />When 2-stroke oils are used within their intended temperature limits, they provide an adequate protective film between all moving parts. But when the maximum temperature is exceeded, the oil film breaks down and seizure can happen, unless another line of defense is added to the oil mixture. These are antiwear agents like Zinc Dithiophoshate which remain in the oil and are never used unless the base oil breaks down. If the base oil breaks down, they form a protective barrier between the moving parts like piston skirts and cylinder walls.<br /><br /><br />
by LubeDude - Many of the better outboard oils are formulated now to run in air cooled applications also.
They would have to be (dual) rated TC-W3
and JASCO FC/API-TC/ISO GC. <br /><br />No oil can do everything best. And remember, the ratings are based on how the oil prevents wear, keeps the engine clean, and its biodegradability, etc. Not whether or not it's a synthetic or non-synthetic. IMO, an engine recommending a TC-W3 oil should simply use a TC-W3 oil, not an oil that also works in air-cooled situations.<br /><br />
by LubeDude - Many people have been using there TC-W3 oils in there lawn and garden equipment for years without problems, However the oil will not adaquatly lubricate in a severe situation, but most do not abuse there equipment so that nearly never comes into play.
In this case, when talking about "adequately lubricating", it's not the "oil" that must be considered, but the detergents...ashless and low ash. <br /><br />Chances are the examples you gave did not exceed the lubrication abilities of the TC-W3 oil. That is, the ring-land temperatures were held below 300F where the ashless detergents worked. TC-W3 oils simply do not meet the needs of air cooled engines.<br /><br />
By LubeDude - However using an air cooled oil in an outboard would be worse. The oil would not burn cleanly enough, and it would cause excess oil buildup and fouled plugs in short order.
To the contrary, low ash air cooled 2-stroke oil would most likely just foul plugs and gum up combustion chambers, like you say. But running TC-W3 oil in an air cooled engine could result in catestrophic piston and/or bearing seizure.<br /><br />
by seahorse - As a rule of thumb, there will be more metallic additives in air-cooled 2-stroke oil compared to TC-W3 oil for water cooled outboards.
I am not aware that there were any significant "metallic additives" in ashless TC-W3 oil. That's why it's called ashless.<br /><br />
by seahorse - The heating and "cooling" (contraction) cycles help blow out the metallic ash.
Only heating the ash detergents can remove (burn) them. Temperatures high enough to do that can occur anywhere in the RPM band, dependent on engine design.<br /><br />
by Maximerc - I have a air cooled snowmobile and a liquid cooled one ..the liquid cooled one feels like it has twice the horse power. Even modern dirt bikes are liquid cool to get better power.
There are many reasons for this, but in general the cooler liquid-cooled engines allow more energy to be developed inside the combustion chamber without exceeding temperature limits.
