It is safe. I've used STP injector cleaner on my Z a couple of times plus I use Chevron gas which has "techron", a fuel injector/carbeurator cleaner. It would be a good idea to use it if you experience problems like hesitation, stumbles or rough idle etc. but it can only do so much. I don't think it would fix the problem but might help. Since our Zs our pretty old, you might want to use them to clean out your stock/original injector. Redline's cleaner is supposed to be one of the best. I'd recommend using it. Just more expensive than most. Hopes this helps.
