Are there problems with opti-2 2 cycle oil?

No. Opti-2 oil has been used without a single problem in the go-cart racing industry for years. It's is also very popular in the lawn and garden and landscaping industries because it is a better alternative to regular two cycle oil since Opti-2 works in all two cycle engines. It eliminates the possiblilty of running too much or too little (very bad) oil through the engine.