According to Zaino, the useable shelf life of their Z6 detailing spray just simply says 5+ years, but the bottle I've got is from 1998! (I won a free kit and never really used the spray, the bottle is so old that you can't even read the label anymore!) 
Do you guys think this stuff will still be ok to use until I can purchase a new bottle? (I'm waiting until I see one of the local Zaino reps at a car show since I don't want to spend $13 for shipping on an $11 item!) What's the worst that can happen when using an old bottle of detailing spray like this? Could it cause streaking or will it simply not give as good of a shine?
I just switched back to Zaino again after a few disappointing years of trying other stuff, and figured I should switch to their detailing spray as well. I've got some fresh bottles of the Mother's California Gold and Meguiar's UQD, so would you guys suggest using either one of those over the mega old Z6? Is it really that critical to use a detailing spray from the same company as the LSP you use?

Do you guys think this stuff will still be ok to use until I can purchase a new bottle? (I'm waiting until I see one of the local Zaino reps at a car show since I don't want to spend $13 for shipping on an $11 item!) What's the worst that can happen when using an old bottle of detailing spray like this? Could it cause streaking or will it simply not give as good of a shine?
I just switched back to Zaino again after a few disappointing years of trying other stuff, and figured I should switch to their detailing spray as well. I've got some fresh bottles of the Mother's California Gold and Meguiar's UQD, so would you guys suggest using either one of those over the mega old Z6? Is it really that critical to use a detailing spray from the same company as the LSP you use?