Gentlemen, When using a Redmax Stratocharged engine, you need to use the Redmax oil. I have seen units carbon up when using other manufacturers oil. Also Redmax is very good about warranties when you use their oil. These engines are so delicate, due to the epa standards, that they need the oil from Redmax that was designed by the Redmax techs. In my area, the oil only runs about a $1.00 for a 1 gal mix. I've had no problems with this oil, but have seen problems with other oil in these units.