I highly recommend that dye. Remember, GM has specific dye for the oil, which is different for the antifreeze, which is different from other fluids. If you use dye, make sure it is GM approved for whatever you are using it in.This was my first and only problem with this car and it was just out of warranty when it happened. I didn't want to pay the dealer price, so I went to a mechanic who is pretty well known. I'm sure he'll fix it for free, he's a pretty stand up guy. I think we should've used that UV dye before starting such a big job. Oh well, you live and you learn.