I have heard that dex-cool will damage seals from some ppl if it's put in an engine that wasn't made for dex-cool. Well my car is a 93 z and the car dealer drained the system last winter and put the dex-cool in it. I didn't realize it til a week ago that they did. I didn't think it should be in there so i put the green stuff back in. I didn't realize befor but found a sticker under the hood that says dex-cool only, but the manual says the green stuff. Anyway, i'm guessing the sticker was put on recently. I was wondering if that would hurt my engine then having the dex-cool run thru it?

 

You'll be fine.

 

The issue that comes up when you mix the green with orange coolent is that over time the mix may cause the coolent to "jelly-up". This only happens if the green or orange coolent was not fully flushed out. But if in your case the green coolent was flushed properly you will have no problems. If this any help I had my coolent changed over back in 1996 from green to orange. I had the system flushed properly and have had no problems at all. I also have flushed my coolent 5 times thoughout the lifespan or the car. And it comes out about 1 flush every two years or so. Also when I rebuilt the motor the block looked great there was no rust in the block and no crap in the radiator and water pump. I run a 60% water/40% coolent(orange stuff) and redline water wetter.