I really didn't want to start a thread about the oil but, I will listen to anyone as I'm no guru on saws. However this is my experience with two strokes. I worked for Suzuki and Kawasaki in the late 70's and early 80's at the shop level as a mech/service manager in Vallejo, CA. We sponsored a couple of racers in the motocross with a 125cc and 250cc classes and of course I worked on other multi and single cylinder bikes-mainly enduro bikes. I always had a few of the KH500 and 750 triples guys were trying to keep running because they were beasts to begin with and hard to control. Now I realize motorcycles aren't chainsaws. What I mostly saw that caused engine failure was carbon deposits that would build up either on the piston or head which created a hot spot and a hole in the piston resulted. The next thing was upper end failure of the caged roller bearing. When that went of course pieces did further damage. Occasionally the big end would go and I would rebuilt the crank. There was also ring failure and sticking which led to piston seizure and scoring and then I rebored the cylinder(s). Preventive maint was to scrape the carbon off the head, piston, and exhaust ports. Occasionally there was seal failure on the big end but unless the bike was old, that usually wasn't the problem. The other killers was the leaking air cleaner intake seals and half a days race with that going on would ruin an engine. During this time period Klotz was used by many races. Their logo was "Klotz Wins Races." And you could tell Klotz because it had a special smell. This has been a while ago and I've forgotten all the details about what oils we sold but the big guys (Kaw, Honda, SUZ, Bultaco, etc) were all competing for customers and being in CA. of course the EPA and CARB were beginning to "clean up those nasty 2 strokes." Like the neighbor with is Lawn Boy smoking up the yard, etc. So between competition of the bike manufacturers and EPA/CARB companies like Klotz, BEL-RAY and Amsoil (they being one of the forerunners) began experimenting with lubes, detergents, additives and that is how the mix ratios have gone to up. The idea was to clean things like the air, and engine and to make things last longer. The less unburned by-products there was in the exhaust the less crap collected on the internal parts of the motor so theoretically the hot spots would be lessened, the motor would make more power, and the exhaust cleaner and the spark arrestors would not clog and exhaust ports and mufflers wouldn't become clogged and area diminished. But still the bearings, seals, piston rings had to be lubed correctly. And, if people did not see smoke being bellowed out by people operating 2 stroke motors it looked better.( We all know that there are people out there that hate our chainsaws, at least until a tree falls on their house or across the driveway. Then there are those that wanted to kill loggers in N. Cal. and those idiots put spikes in the trees.) So today we have oils and mixes that are quite different than the 30 to 1 non-detergent 30w mix with leaded premium that I used in the XL923 Homelite in 1970. That saw was still running (it required decarbonizing) until my brother let a tree fall on it last year killing it for good. I started experimenting with the Amsoil syn mixes when it came out in a Kaw Jet Ski I bought through the dealership in 1978. Kaw recommended , if I can remember, 32 to 1 with their 2 stroke we sold in the shop. I decided to try the Amsoil 100 to one mix. After all, if it blew up, I could get parts and I had gone to service school for it, and my boss said if we were going to sell it, then he told me to use it. The Kaw mix blackened the side of the boat and made some smoke and there was some carbon buildup on the pistons. I milled the head 50 thousands and ran a thin copper gasket on the 440 cc motor which pushed the compression psi up to 185 psi from the factory spec of 140, installed better scavenging pipe, and got rid of the muffler, and put a better impeller on the thing. Then I tied it up to a dock, had a friend help me, held the throttle wide open and peaked the motor on the rich side a little using a tach. I kept the mix at 100 to one but, keep in mind at that time I was using ARCO premium with no ethanol and it may have had a little lead in it but I tend to think not. This was in 1979. The blackened side of the boat went away, and for a 440 it really ran good, used a little more gas but WTH. My co-worker decide he would build his ski. He punched it out to 475 cc and milled the head, etc. He could pull me in a drag race but on top end I think we were about even. The 475 made more torque out of the water but didn't spin the impeller fast. I had just redone the head and was planning on running my Jet Ski down at the Ozarks in the summer of 2012 and it with my saws, burnt up in the fire.
Now getting back to the saws, my two weed eaters, and the Lawn Boy. Per advice here I have been running the 80 to one and I checked to see the difference between that mix and the 100 to one, in the 445 and the 372. The plugs electrodes in the saws are almost black and there is oil build up around the threads. With the 100 to one the electrodes were a tan color. So there is a difference here. I didn't check the spark arrestors with the 100 to one but with the 80 to 1 there is carbon build up but not to the point of clogging it. I called Amsoil and they told me not to go lower than 50 to one. I will try that later when I get more gas to mix and report it. But in no way will I let the motor get carboned up. The only thing that I really don't know is how different oils and gasolines effect the seals and how they hold up.My Jet ski had the original seals. We had a Lawn Boy mower that we got in 1989 that ran until 2012 on it's original motor on the 100 to1 using all the bad fuel that CARB threw at us in CA, including the MTBE/ethanol mix. We all know what happens if seals leak. Oh, the Lawn Boy burnt up, too.
It hasn't blown up yet? I guess that says something right there! I still wouldn't do it.
