Can this be used to patch a gravel driveway?

This is a great patch for asphalt driveways when properly spread, tamped, and sand coated (to prevent tracking) but NOT for gravel roads. I maintain both asphalt and cement drives and a private gravel road that is shared by many maintenance contractors and 5 families with mostly speeding drivers. I have GREAT success patching the asphalt and concrete with this QPR however the gravel road sees far too much abusive vehicle traffic and rain run-off so I use what is commonly referred to as "crush run" or contractors gravel which is designed to make gravel roads and usually found at your local quarry in bags and bulk. The closest thing Lowe's has is their "Rock City 0.4-cu ft Landscaping Rock" Item # 12919. The more loose grit that is packed in the bag with it the better as it acts like a porous mortar if it gets in the repair area. Fill to slightly dome the repair area, tamp, and step away and let traffic pack it down. Just like gluing wood, it will be the only spot you won't have to patch again.

From my experience it should hold up okay IF the base is solid and you tamp it really hard into the hole. We've used it that way and it has held up for 6 months, including several heavy rains.

You can certainly give it shot. It may not work as a permanent solution, but it'll probably work better than anything else you can find to do the job. Just follow the directions as best as possible with your particular situation, most importantly, make sure any holes you patch mostly free of loose debris & have a hard surface at the bottom. You can even sweep a small amount of the loose gravel on top of the patched area to help the surface be ready immediate traffic. Hope it works for ya if you try it, I'd be very interested to see how it turned out over 6 to 12 months

No, this can not be used to patch a gravel driveway.