Welcome! You have a lovely machine. Like others have said, sewing machine oil is what you need to use, no synthetic grease in the motor on this beauty. This machine has a different motor than most and its wicking system needs a low melt grease, in fact Singer recommended using Vaseline as a replacement for the original Singer motor lube which is no longer available. A couple of on line shops carry their own line of expensive lube that they tout as the best replacement for the original Singer lube, but I'm not convinced it's any better than Vaseline.
Cari