A couple years ago I started using Pentofrost A2 green, which is POAT - Phosphate Hybrid Organic Acid type. Now it's hard to find, for me anyway (I only buy concentrate, not "pre-diluted"). Looking on Rockauto, I found BeckArnley Red Concentrate, which is also POAT, and as a plus it's cheaper than the Pentofrost. Can I mix the BA Red with my remaining A2 Green? This is for a 22 year old GM car, so there are no warrantly issues or anything like that.