Thank you, I ask this question because I’ve seen where some people will be really old school and run SAE 30. I suspect that you are probably mixing it a tad rich, which will not allow the oil to be completely burned, resulting in oil in the muffler. My suggestion to customers who do this is to switch to a straight synthetic, such as Opti-2 which is a multi-ratio oil. Eliminates all mixing problems. Just my opinion.