I don't have a source of the Singer Motor Lube any more. From what I have read that lube has been discontinued by Singer and what you find now ( the white stuff ) is for gears, not motors.
To use petroleum jelly go to Sew-Classic or a craft / hobby store and buy one of the syringes with the long curved tube on the end. Pop the plunger out and fill it with petroleum jelly then put the plunger back in. You'll need to cut the tip off the curved end so it will just fit inside the motor grease tube. Insert and inject.
I keep two of those syringes, one with Singer lube - eventually will have p-j, and the other with T-F grease. They are very handy.
Here's the Sew-Classic link so you'll know what I'm talking about
:
{
http://www.shop.sew-classic.com/Syri...e-SCSMJ412.htm }
Joe