There's no such thing as 16x rated DVD+RW or DVD-RW media.
If you have 16x rated media with an "RW" logo, the discs are recordable but not re-writeable; i.e. they can be burned once. The "RW" logo was chosen by the DVD+R alliance for use on both +R and +RW media - a very bad choice in my opinion, since it confuses a lot of people.
If you have DVD+RW media, it must be rated 2.4x, 4x, or 8x.
DVD-RW media is rated 1x, 2x, 4x or 6x.
In theory such discs can be overwritten a thousand times if done properly, but in practice they tend to become bad due to scratches and scuff-marks before you reach the 1000 re-writes.