Wow, good work and thanks for sharing the results! Your results are very interesting. A couple of comments...

What type of oil were you using? I was just reading recently that some oils mix better with methanol than others.

Also, where did you get your ether?

Any possiblity of running one more test and substituting acetone for the ether? Acetone is much more readily available, and might make a more stable mixture to have around. I'm thinking the volatile ether would evaporate if you weren't very careful with your fuel cans! You might have to use 10% instead of the 5% you used with ether, but it would be interesting to find out. Acetone instead of ether might eliminate the "kickback" that you experienced as well.

Thanks again,
AV8T0R