I'm doing a coolant flush on a friend's V70. Right now, I have no clue what's in there but it appears to be mostly water--so I'm not going to worry much about the original coolant, I'm just going to flush the system. Can G-05 be used as a substitute for this stuff, or should I just have him pick up the G-11. O'Reilly's actually stocks Pentosin G-11, which is what was in the car originally (it's crazy expensive though, and given that the car is running on straight water now, seems like overkill). I seem to see conflicting things, and I seriously get a headache every time I read about coolants. Seriously, does it really need to be this hard? Why are there 24 different coolant specs?