Oh boy a two cycle oil ratio thread! Let me get my popcorn!
I might as well chime in with my thoughts. I have a dozen small air cooled two cycle engines that I like and use. The engine maker's all spec the oil and oil ratio that they would like me to use in their engine. Also they spec the octane of the gas and some spec that no alcohol blended gas be used in their engines. My engines call for oil ratio's as rich as 16 to 1 and some run up to 50 to 1. Some of you are running 100 to 1 with special oils that have somehow been designed to hang around for a few seconds longer than the run of the mill dino oil that is out there. Typically two cycle oil is just passing thru your engine but if you have enough of it all is fine. If you don't then things get rough for the inside of your engine quick. Most people think that if they run the ratio too high the first thing they will trash is the piston and cylinder wall, but this does not seem to be as much of a problem as it was when two cycle oil was just 30w with little if any additives, and this stuff was ran at 16 to 1 smoked and stunk to high heaven. Today we have much better oil and additive packages to cut down on smoke, carbon, plug fouling and other nasties. With these better oils we can get away with running higher ratio's but why would we, do we know just what is happening at every second inside the engine or just guessing. So I have always ran what the manufacturer recommends for ratio's or richer and I have had no problems whatsoever. Most of my engines other than my lawnboys spec 50 to 1, most have never seen leaner that 32 to 1 for the same reason that some here will choose the higher ratio for multiple engines. I just don't want to have to keep several different ratio gas cans around. The second thing I do is I use the same oil for all the air cooled two cycle engines, Mobil One Racing Two cycle oil. I have a lifetime supply of this oil and it is fully synthetic oil, smokes very little and works very well in all my engines at 32 to 1. I have actually tested it and it reduces the temperature at the spark plug on my Lawnboy duraforce engines. I don't get carbon build up and have never needed to pull a head to de-carbon a piston, head, or exhaust port/muffler. With today's two cycle engines running lean due to EPA mandates for emissions this strikes at the very heart of a two cycle engine's desires as they like to run rich. I hear about people saying that they don't like the smoke from a two cycle engine so they like to run oils that the oil maker spec's at a high ratio and it does indeed reduce the smoke but at what cost? If you don't like exhaust smoke then get a four cycle. Oil is the life's blood of the two cycle engine, I would never starve it for my own comfort. Some say that richer ratios will lean out the engine and cut down on the power, my answer is to just adjust the carb a little to make up for it if you feel it is happening. More oil in the mix does not reduce power, it increases it due to better ring seal. This has been proven by the outboard racing folks whom have run ratio's as high as 8 to 1 and they have seen power increases but the engines did not want to idle and blew oil droplets out the exhaust. For those that want to run lean oil ratio's I would recommend full synthetic oils designed for the service you are using it for, air cooled or water cooled because the additive package will be correct then. For those that want to run automotive four stroke oil in there two cycles your on your own, the wrong additive package and base oil will shorten the life of the two cycle engine.
For those that noticed that their two cycle smoked a lot more at cold start up: The oil on the internal parts drains off and settles in the crank case. The engine is choked which will richen the mixture and provide even more oil. There is little heat to help the gas oil mixture separate and large oil droplets ten to smoke more. When the engine gets up to temp the droplets become vapor and burn cleaner, the crankcase is washed out of excess oil and the smoke lessens. Dino oil tends to burn and synthetic oil tends not to, which lessens carbon build up as only the gas contributes to the carbon build up.
My bottom line: Mix a high quality synthetic oil at the engine manufacturers recommended ratio or richer.
Adjust the carb to the correct engine running rpm.
Keep the cooling fins clean.
Don't use alcohol enhanced fuels if you can help it, Alcohol bonds with water and settles to the bottom of your tank leaving gas and oil above it, most tanks take fuel from the bottom of the tank where there is no oil, the rest is no fun. If you are forced to use alcohol/gas fuel then shake your can well to re-distribute the alcohol oil mix. Keep your can sealed from the air and mix small amounts at a time to keep water absorbtion down. Don't mix up more than you will use in 30 days and keep the gas can and fuel tank caps sealed when on in use.
Just for fun, get a quart jar with tight fitting lid. fill it half way up with gas alcohol mixture, put in an ounce or two of water, 1/2 oz. of two cycle oil. Lid it up and shake it, then set in on a shelf for a few days then come back and take a look. The alcohol will absorb the water, settle to the bottom, water and oil don't mix well so the alcohol and water will be oil free, at the bottom, where your tank outlet is. A minute of running on alcohol and water and no oil, well you get the picture.
Good luck to all here, treat your two cycle engines right and enjoy them.
