I thought that all electric heaters were 100% efficient.

What is this site talking about when they say:

"During the process of converting electrical energy into heat energy a
great deal of it is lost. Therefore an electrical heater is left with
45% of the energy for heating purposes."

http://recomparison.com/comparisons/...diant-heaters/

P.S. I'm back to struggling with whether or not I should use a
constantly running oil-filled heater (set on low) in my small workshop
or should I run a small electric heater with a fan only during those
times when I'm in the shop, usually a couple of nights a week and a
few more hours on weekends.

I have both, so the initial cost is not a factor.