Can Family Tree DNA help me?

[Jonesy]

The surname I am researching, Rivolta, gives no results when I search the Family Tree DNA site. So is there any point in doing any sort of test?

I am British, I'm male and I'm researching my maternal grandfather. It would appear he was illegitimate. He had no sons.

[vinnie]

Given that your maternal grandfather had no known relatives other than his wife and children, the only test that could possibly help would be Family Finder in the hope of finding a cousin who could lead you to your grandfather's paternal line.

Here's the strategy:

Have your mother or one of her siblings test and upload the results to Gedmatch for a wider group of people to match against.

If that's not possible, you test, but also have your father or one of his siblings test so that you can determine which of your matches comes from each of your parents, and/or test one of your mother's maternal line relatives to compare your matches against his/hers.

FWIW, there are 80 Rivolta records at the Ellis Island site; you may be related to one of them if that was his real surname, whether it was his father's or his mother's.