@Vincent BergI found this post that discusses possibilities and comes down on the side, generally, of nothing. He claims:
"Setting off a character's thoughts in quotation marks is a definite no-no. Such a technique is confusing to the reader. When we see quotation marks, we have the expectation that a character is speaking the words aloud."
The example given is Deception on His Mind by Elizabeth George. I got a sample from Amazon. It's close third person with a LOT of internal focus. And no quotes. I find myself doing this also, when writing third person very much in the head of a character - the line between writing what the character thinks, decides, concludes, or judges and the exact language of those thoughts is VERY fine. Here is an example from a chapter I happen to be editing in book 3 of my series. Katie is on the phone with her mother:
There it was. That lilt in her mother's voice. Even a surprise collect call on a Monday morning didn't push her into the sullen defensiveness Katie had grown up with. What was going on? She needed to find out.
"Just missed you, Mom," she said, truthfully. Despite her mother's despondence, she had always taken care of Katie, shown interest in her life, and been available when needed. But she had also become the "don't do this" model for Katie. She had structured her approach to life as the opposite of her mother, friendly rather than aloof, light-hearted rather than serious. Now, her mother was changing. Why? What did this mean?
And, a couple of paragraphs later:
Yes, you told me, Katie thought. And why is that, I wonder? All of a sudden, you're a businesswoman, reconnecting with the town, and making moves toward picking up your old career. What is going on, Mom? But she kept those thoughts to herself. Instead, she said, "Yeah, Mom, you did. But that won't be a problem. I'll just be writing, and maybe picking up some shifts at The Diner if they need me."