I ONCE RUINED MY 2 STROKE MOTOR MOWER ENGINE BY USING MARINE 2 STROKE OIL IN IT AT THE RECOMMENDED RATIO OF 25:1. SO, IF IT'S AIR COOLED , IT NEEDS BETTER/HIGH TEMP. OIL. MY DAD ONCE OWNED A 1940'S EVENRUDE ELTO LIGHT 4 OUTBOARD. IT HAD ALL BUSHED BEARINGS, WITH ROTARY VALVE INDUCTION AND NEEDED AN 8:1 RATIO. YET IT WORKED VERY WELL BUT SMOKED A LOT. BACK THEN, SAE 30 OIL WAS ALL ONE COULD GET FOR IT. (I'm sorry now we ever sold it for more power)2 stroke air cooled engine oil Not water cooled engine oil i.e. 2 stroke marine oil. As for the ratio it depends on the engine size and type of oil. Generally the smaller the engine size the greater the oil ratio. Oil ratios can go from 16:1 to as high as 100:1 but once again it depends on the engine, engine size and type of oil. With todays 2 stroke air cooled engine oil I usually run between 30:1 & 40:1, 25cc & 440cc. I have a very old circa 1966 250cc 2 stroke and I run that at 25:1 giving that extra oil so less wear but, poor power. On my 10cc glow engine it runs good at 15:1 oil/alcohol no nitro. I find Stihl chainsaw oil to be one of the best and go by what they recommend.