Have a 97 turbo wagon. Decided to change the coolant because it had been in there a good number of years, and, knowing that it lubricated the water pump, I decided to change it out. The owner's manual said the system contained 7 liters, and showed a diagram of the drain points. The coolant level in the reservoir as between min and max, so I know I wasn't down. I slid a pan under the main pet cock, opened it, and drained out about 3+ liters. The pet cock on the back of the block yielded about another cup. Disconnected the hose at the bottom beside the pet cock ala Haynes' instructions (surly a redundant operation, since the pet cock is only one inch away from the hose clamp),and it yielded nothing. All in all, max 3.5 liters. That left 3.5 unaccounted for. Looking for that magic drain I overlooked, I finally gave up and poured the radiator full (3+ liters of hot water) until the reservoir was almost at the top, started the engine and waited for the fan radiator fan to come on to show that the fluid in the block was circulating with that in the radiator, and, after about ten or fifteen minutes, shut the engine down and drained the radiator. The water was bluish green, which told me I had flushed some of the hidden 3.5 liters out of the system. I did this three more times, and then said to heck with it, and poured in two liters of Volvo's antifreeze, undiluted, and then diluted the rest 50-50. Started the engine and waited for the temp needle to spike which would say the coolant was too concentrated, but it did not happen. After driving a bit and working the air out of the system, I managed to pour in about another two and a half liters of mix from the four liter container, leaving me with one and a half. Well, not bad, considering the system only holds seven and I managed to get almost all my concentrate in, but I am at a real loss to know why I couldn't drain all seven liters out of the system, and, whether dumping undiluted antifreeze into the reservoir to mix with what I couldn't take out, was a smart thing to do. If I had cut the entire 4 liter container fifty fifty I would have wound up with eight liters of diluted antifreeze, of which I could only have gotten in about three or four, which wouldn't have given me the protection I needed. Any explanations? I've done my share of stupid things in my life, but I hope this wasn't one of them. Dick