I have done this with an old Pioneer 4x using Taiyo-Yuden 8x.
I would suggest, however, that you use Nero CDSpeed to check the burn and compare it against the quality of the burn you get with the same media on your more modern burner.
If you have the latest firmware installed in the burner, yes, and thats if they created firmware that would recognize 8x. Then again you can try it and see what happens. Have a fire extinguisher handy.
JJK