No. You don't want to use a synthetic grease in the motor. You need to use one with a fairly low melting point. You can buy into the hype and use the grease that's for sale in the little syringes on the featherweight websites or you can get a small syringe and use Vaseline. It's almost the same exact thing as the old style Singer lube, and in fact in the manuals for some Singers and Whites that I know of even recommend using Vaseline(petroleum jelly).
Cari