Here's my $0.02. 3 years ago on my V70 98 I decided to change the coolant. I went with Dexcool and had it for couple of years and there were no issues with it, except for one. When heater was turning on I could smell a faint coolant odour for a brief period. There were no noticable losses, heater core seemed OK (no wet carpets, etc) except for the smell. So, last year when another flush was scheduled I used Volvo coolant and the smell was gone. My take on that is that the gaskets' (o-rings) material on the heater piping connections was not 100% compatible with Dexcool and let a drop or two before pressure and heat would help them seal completely.