dark_jedi said:

Depends on the brand, some do not even last 6 months, I have Verbatim DL's that are 3 & 4 years old and still read great, also I don't think anyone uses DL -r's, only +r's.

-R's are more popular in Japan than +R for some reason. I think I read somewhere that Taiyo Yuden didn't support +R DL because they found them unreliable to manufacture in high quality or high volume (or something like that), which is why they only make +R SL discs.

There is a lot of useful info at the site below about who manufacturers what discs and what countries they come from and what brands are recommended buy or avoid etc

http://www.digitalfaq.com/reviews/dvd-media.htm

Hope this helps.