It all depends how the discs are encoded - what speeds they indicate to the drive that they'll work at. If the drive can't figure them out, then it likely simply won't burn on them.

Quite a while ago I purchased a bunch of 2X DVD-R media at CostCo and despite all the printing on it my drive recognized it as 4X and they all burned correctly at that speed. But then I was reading that old CD-RW media (4X and under) *cannot* be used in drives that support the far higher speeds, since the dye was changed. Of course I was reading about that after wondering why I was burning garbage with my new drive. :-)