Redline Allsport is a low-ash synthetic designed for air-cooled motors. I read all the literature on their website and I believe it's the best choice for an air-cooled model engine. I could be wrong though, it happened once before around 1963......
From what I remember reading, their racing oil has a higher film strength, which isn't bad, but the only oil that was specific to air-cooled engines was the Allsport. I haven't been inside my 2 gas engines to judge how clean-burning it's been. The Allsport leaves a red film on the covering that is easily wiped off. I never tried the racing oil.
Borrowed from their website, this oughta clog up the system:
INFORMATION
SuperClean Two-Cycle Oil - the cleanest two-cycle lubricant available, in fact, we have never encountered a two-cycle application where our SuperClean Two-Cycle Oil caused deposits. It is used in heavily modified engines which operate at temperatures well above a stock engine and burns extremely clean, leaving little residue in the combustion chamber or exhaust system. The scuff protection is very good, although not quite as good as the Two-Stroke Racing Oil.
Two-Stroke Racing Oil / Two-Stroke Kart Oil - provides cleanliness which approaches the SuperClean Two-Stroke Oil, but formulated with additional lubricity to keep even the highest-revving engines perfectly lubricated. Terry Ives Industries obtained perfect engine condition in their 100cc Yamaha KT-100 school karts after 25 hours of use. In this same type engine under 3 hours of competition at 20:1, the piston clearance increased only 0.00025 inch. Racing castor would provide between 0.001-0.002 inch wear under the same conditions. No ring, ring land, or cylinder wall wear was apparent in this 3 hour engine and skirt scuffing was virtually eliminated. In the Rotax 256 In-line Twin and the 125 Single the results were equally impressive. No obvious wear could be seen and skirt scuffing was virtually eliminated. No carbon deposits were formed and all combustion residue was easily wiped clean. Plug life is greatly extended. Emmick Enterprises obtained similar results in a Yamaha KT-100 which operates in the 350°-420°F cylinder head temperature range and up to 15,000 rpms. No scuffing and very low wear were observed after 7 hours competition. A measurement of the lower-end bearing indicated that Two-Stroke Racing Oil provided less wear after 7 hours than racing castor or other synthetics after only 45 minutes. Many kart racers report that they can operate their engines at temperatures of 25°F greater than when using racing castor or other synthetics, without fear of piston sticking, enabling a considerable increase in power to be obtained. Two-Stroke Racing Oil is also exceptionally clean and this cleanliness makes it an extremely popular lubricant for jet skis, where it provides very crisp throttle response, up to 2-3% improvement in power, and will not leave a sticky residue in expansion chambers, waterboxes, or down the sides of the ski. We have several years experience with this oil in V-6 outboard racing in Champ Boats and Off-shore racing where it provides improved power, half the wear of other high-quality oils, and perfect cleanliness in even endurance racing. Dyno tests have shown 2-3% improvement in power, using a fresh engine, but the actual improvement is considerably greater compared to other lubricants. As the engine wears and develops deposits which restrict ring mobility and increase backpressure in the exhaust, the power output declines. But with Red Line Two-Stroke Racing Oil the reduced wear keeps the engine fresh and the complete absence of deposits keeps power output high. Two-Stroke Racing Oil can be used as a premix or as an injection oil.
Two-Stroke AllSport - is a high-performance all-synthetic formula which is designed to provide maximum power and the greatest protection and cleanliness in watercooled and air-cooled two-cycle engines. The properties are the same as with the Watercraft Oil above, but uses a low-ash chemistry which provides better cleanliness in higher temperature air-cooled engines, while the WaterCraft Oil provides better cleanliness in lower-temperature water-cooled engines. Recommended for high-performance stock or slightly modified engines and where ISO GD, JASO FC, or API TC lubricants are recommended, but is not designed for outboard use. Red Line AllSport Oil may be run in ratios between 16:1 and 100:1, depending on rpms and engine manufacturer requirements.
Two-Stroke Smokeless - is a high-performance synthetic formula which is designed to reduce exhaust smoke. All Red Line two-cycle lubricants produce very low smoke, but with Smokeless it is virtually non-existant. The synthetic basestocks completely thermally decompose in the combustion process, helping to reduce petroleum pollution. This lubricant also has excellent high temperature lubricating ability - much better than petroleum and many other synthetics - providing less smoke, and clean spark plugs, pistons, and power valves. These basestocks are combined with low-ash deposit control and anti-scuff additives to prevent ring-sticking and scuffing under extreme temperatures and keep the piston and exhaust ports clean. The slipperiness of Red Line Smokeless Oil can produce more power and can provide significantly longer bearing life than when using manufacturer's oils or other synthetics, even in oxygenated gasolines. The low-ash chemistry provides better cleanliness in higher temperature air-cooled engines. The thermal stability graph shows the Smokeless providing better cleanliness than petroleum lubricants and it also provides significantly better scuff protection, but for significantly improved power production any of the other Red Line two-cycle lubricants are superior. This lubricant also has excellent high temperature stability - much more stable than petroleum or other types of synthetics - providing less smoke, and cleaner spark plugs. Recommended for high-performance stock or slightly modified engines and where ISO GD, JASO FC, or API TC lubricants are recommended, but is not designed for outboard use.
New Ring Seating - Red Line Two-Stroke Racing Oil generally should not be used to seat a new ring because of the extreme slipperiness of the lubricant. A petroleum two-cycle lubricant used at normal loads for 15 minutes should be adequate for ring seating. Red Line Two-Stroke Oils can be used for ring seat if the engine is operated at 80% load for 15 minutes immediately after start up. Red Line is compatible with petroleum lubricants, so system flushing is not necessary.
Compatibility - Red Line Two-Cycle lubricants are compatible with petroleum, castor and most synthetic lubricants. They may be mixed together in concentrated form or the fuel without separation or gel formation.
Mix Ratios - proper mix ratios should be determined by the engine builder for the application being considered. Choosing the proper ratio depends on bearing and piston design, piston clearance, rpms, and air:fuel ratio. Higher rpm engines and those operating at high cylinder head temperatures require more oil in the fuel to maintain proper lubrication. When switching to Red Line Oil, begin with the same ratio at which other lubricants have operated successfully. Red Line Two-Cycle lubricants will allow the leanest oil:fuel ratio of any product on the market. If other lubricants have successfully operated at, for example, 100:1, then the Red Line lubricant for that application can also be used at the same ratio. After reviewing the performance at a given ratio, the amount of oil can be reduced slightly, to determine whether the reduced ratio is satisfactory or whether additional decreases can be achieved. A significant advantage of the Red Line Two-Cycle lubricants is that rich oil:fuel mixtures can be used without significantly altering the combustion characteristics of the fuel and still provide excellent throttle response. As a starting point, the Two-Stroke Racing Oil is generally operated at ratios between 16:1 to 32:1. The Two-Stroke Racing Oil is used at mixtures of 24:1 to 32:1 for 9,500 rpm outboard race motors, 50:1 for high-output operation, and up to 100:1 if the engine is properly designed for reduced oil mixtures. The Two-Stroke Watercraft Oil, Two-Stroke AllSport, and Two-Stroke Smokeless can also be operated at ratios between 24:1 and 100:1, depending on the designed lubricating requirement.
Summary of Two-Cycle Recommendations
SuperClean Two-Stroke Oil - For highly modified engines which have severe deposit forming problems and still form deposits using the Racing Oil.
Two-Stroke Racing Oil / Two-Stroke Kart Oil (they are both the same chemistry) - for highly modified racing engines which turn high rpms, such as racing motorcycles, karts, personal watercraft, snowmobiles, and highly modified outboards.
Two-Stroke Watercraft Oil - for stock to moderately modified outboards and personal watercraft where NMMA TC-W3 or any TCW lubricant or other ashless lubricant is recommended. Two-Stroke AllSport Oil - for stock to moderately modified motorcycles, snowmobiles, garden equipment and chainsaws or any two-cycle engine which recommends a low-ash type of lubricant.
Two-Stroke Smokeless - for stock two-cycle equipment which requires low-ash chemistry and there is a desire to completely eliminate smoke.