Magnum and OS are pretty much same engines. Looks and performance wise. I have gad a couple Magnums and never had any problems. OS are a bit more expensive and they have a better reputation. It up to you. On my Magnum .52 i use 15% nitro and 18% oil mixture fuel. Pretty much any kind around that ratio will work fine. At summer, i drop the nitro to 10 or even 5%.

I am glad you decided on .52. Good choice!