I run saitos as well, and use a mix of 15 % nitro with about 17% oil and have had no problems whatsoever. In my .56, I prefer to run 30% heli fuel as I feel it gives me a more consisten run, but in my larger saitos, I just use regular 15% airplane fuel. I don't think the oil content was the problem, especially given the one and 1/2 tanks he ran through it. Now, the previous owner may have ran it lean for quite some time, causing cylinder damage. However, I would point more to just faulty sleeve. BTW, I didn't realize saitos had chrome sleeves--guess you learn something new everyday. I thought they had cast cylinders with aluminum sleeves.