I would'nt rely on Amsoil warranty one bit, but today people feel safe with a little false security. FWIW Muffler spooge has as much to do with how you tune your saw as anything else. I've yet to see an engine failure directly related to oil. 100:1 will work fine, just don't expect maximum service life out of your gear. 100:1=1%oil, 50:1=2% 25:1=4%. You really think running 1% oil compared to 2% makes a big improvement...... stops black spooge? Lol this is getting funny.