Has anyone here refinished red oak floors to a lighter shade than natural? I guess they use a stain to somehow make the wood appear lighter. How did it turn out for you?

Red oak is pretty light in color, so if you are looking for a lighter color it all depends on the stain you apply. Can go for natural oak color to any color darker that you want. My guy custom mixed colors based on what I showed him pics of and my final desired outcome. I chose the one of the three samples he applied to my floor I liked best, after poly it looked very close to what the samples looked like. Oak with no stain is pretty darn light in color.

He sanded the other test swabs off the floor before applying my custom mix.

I have red oak flooring through my whole house. Most of it is stained dark, but the master bedroom is only clear coated. It is very light in color.

I had worked with a guy who put red oak throughout his house too. He wanted the red oak to be lighter than natural ... and used a very light white stain on the red oak. Looked good.

rubio monocoat has lots of stain colors.

https://www.rubiomonocoatusa.com/

They claim it takes a pro to put it on.

It is not a shiny finish.

My neighbor had it done on their oak floors.

It looks good, but not my taste.

I have red oak floors sanded and polyed.

They start off very light and get darker to a honey color over time.

Is it stained? Red oak is actually pretty light.

Red oak plus red oak stain darkens it pretty close to finished sapele in my informal testing.

In a small section you could try stripping it to the wood and sand to see if it changes color. If that's the case you can go with a more natural shade when you refinish. Use something UV resistant for the clear.

If that's still too dark you CAN bleach the wood but I've never done it on a small project let alone an entire hardwood floor so I can't give any guidance.

I have used a water based pickled oak type stain on red oak furniture with a water based clear finish. Turned out well with a much lighter color. Not sure if it is durable as oil based floor finish.
Most all oil based finishes tend to yellow and darken somewhat with age.

Oak turns black on contact with water, how are they able to use water based finishes?

For the most part it takes bleach to lighten it if sanding the old finish wont go far enough. A white "stain" is actually a white pigmented paint. I've had that issue where I wanted a clear tinted stain and wound up with a latex paint looking finish. Not acceptable except the last time we did our deck, which is over 35 years old. Hides a lot of wear and tear, fills the cracks, looks like blonde floor paint. "Stain" is a newer definition that older remodelers discovered was redefined. You know, like, "vaccination."