Welcome to CD Freaks.
First: Your drive is old and out-of-date [in the fast-paced world of technology]. You won’t have much luck with ANY 8x DVD+R DL media [or any DVD-R DL media].
Second: Since your drive is rated to write DL at 2.4x, you’ll want to stay with discs rated for 2.4x.
Third: only buy Verbatim DL media. You won’t likely get usable results with anything else.
 Fourth: See the post below this.
Summary: buy Verbatim 2.4x DVD+R DL, and make sure that you can actually recover the data after the discs are written. If, after trying to use Verbatim 2.4x DVD+R DL, you are unable to get a usable DL disc, just go back to 8x rated single layer media, preferably made by Taiyo Yuden and/or branded Verbatim. This will ensure that you have good results that should last.