Coolant flush safe?

Starting my t-belt/waterpump job in the morning. I think I want to flush the system today though to cut time tomorrow. The paranoid guy in me is wondering if the prestone coolant flash chemical you buy is harmful in anyway to the gaskets or seals in the motor. I'm not talking about immediate harm but more like does it cut the lifespan of gaskets and seals it's come into contact with.

I guess I'm looking for horror stories with the prestone type flush stuff. Anyone?

 

When I changed my timing belt/water pump and radiator (two separate incident), I just drained (not flush), do the work and filled with fresh red coolant mixed with distilled water. I don't think a true flush is needed unless you're switching to green coolant afterwards.

 

If your coolant is in good condition now, I would just flush it with fresh, clean water. The Prestone flush is what GM had us use to clean out the contaminated S10 cooling systems years ago. We had no side effects using this product.