This is a reoccuring subject, and I try to keep an eye on the latest info. You can use lithium grease on the gears, but not the motor. Vaseline works well, it's purified mineral oil of the right kind. The gears will run a notch or two smoother on other greases like Triflow or Finish Line Ceramic Grease, these are the clear more transparent (whish to opaque might describe them) and they have teflon. Lithium greases tend to last longer, but there are smoother greases available. Vaseline will never be wrong for the motor, but if the original type singer grease will appear again in small tubes or tubs, it might have some advantages.