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My impression was that Amsoil had been tested and ran the best at that ratio. I called them. They said they had used it in Lawn boys at 300:1 and had no issues. My question:
No, testing at 100:1 or 300:1 doesn't mean the machine made more power (ran better) at that ratio, it just means that it ran and didn't lunch itself, a big difference.
This is my theory. Most oil from other Mfrs. mixes would have a lower flash point and would burn a bit. This would add to the combustion energy. I notice in Amsoil pro mo material their oil does not burn off at working temp. Well if it does not burn it would not smoke and more oil would be left to lubricate the engine. This would explain less smoke and better lubrication at higher mix ratios. I wonder if this is correct?
No. Just compare flash points (and I've listed a heap in the past)
Amsoil Sabre ATP 114*C (Not JASO licensed)
Stihl HP Ultra 222*C (JASO FB, Castrol Europe/Omni lubricants US)
Castrol Power 1 Racing TTS 76*C (Australian blend, JASO FD license)
Castrol Power RS TTS 70*C (US blend, JASO FD license)
Castrol R2 Racing Bike 87*C (Australian blend, JASO FC license)
Castrol A747 274*C (GP racing bike oil, castor/synthetic blend)
Castrol XR77 223*C (Current GP racing bike oil, full ester synthetic blend, replaces A747 in extreme use)
Dolmar synthetic 2 stroke oil 99*C (US Blend, Spectrum Lubricants)
Elf HTX 909 270*C (synthetic/castor blend, kart engines, up to 25,000RPM)
Elf HTX 976 208* (synthetic, GP bike blend)
Husky XP oil 102*C (US blend, Spectrum Lubricants)
Klotz R50 204*C (synthetic)
Klotz Super Techniplate 238*C (syn/20% castor blend)
Mqaxima Castor 927 216*C (castor/synthetic blend)
Mobil 1 Racing 2T 110*C (Australian spec, JASO FC license)
Motul 710 88*C (JASO FD)
Motul 800 2T Off Road 252*C (GP MX blend)
Motul 88 2T Road 274*C (GP road bike blend)
Redline Racing 103*C
Redline Smokeless 82*C (equivalent to Ams Sabre, for chainsaw/OPE use)
Silkolene Pro 2 210*C
The JASO FC/FD oils generally have lower flash points to minimise smoke and meet the cleanliness requirements of the JASO licensing (and Sabre isn't licensed)
The race specific oils have pretty high flash points, and yet the full syns have minimal smoke anyway, as a few fella's have noted above.
In my case I use Motul 800 2T OR @ 40:1 and note little to no smoke or odour in use.
You need oil for ring seal, as well as bearing protection and piston skirt scuff protection.
The more oil, the better the ring seal (and skirt scuff protection). To get piston skirts to survive at leaner than 50:1 ratios that the manufacturers have designed for, the blender needs to load the oil with greater amounts of Anti-wear (AW) and Extreme Pressure (EP) additives and it will work, but what about ring seal ?
Dyno testing has proven that fatter (richer) oil/fuel ratios make more power and it's all down to sealing the combustion chamber during the firing/combustion process. Probably doesn't matter in a little strimmer, but it's a big deal in bikes/karts and a few people that run saws.
Chainsaws develop minimal BMEP (brake mean effective pressure) compared to other high performance two strokes. This is just a fancy engineering term for less specific power than kart and GP bike engines, which are developing over 400BHP/litre these days. As a consequence HP karts still use around 16:1 mix ratios to prevent seizing.
The interesting thing is that the oil companies often recommend changing to their racing oils from their high performance synthetics at around 14,000 RPM. Saws also cop a caning in terms of temps as they often have their fins blocked with chips and dust, so to my mind why skimp on mix ratio ? 32 to 50:1 is cheap insurance IMO.
Basically other oils must be used at 50:1 because some oil is being burned and less is left for lubrication.
Thanks in advance for the help.
I think I've put forward my thoughts above
