Coolant Leaking problems of the 1999 Chevrolet Venture

The problem with my Venture turned out to be a leaking water pump based on the mechanic's diagnosis. So far, so good. Although, replacing a $300. 00 water pump at 82,000 is somewhat ridiculous! the mechanic says it was due to the fact that the extended life coolant (dex-cool) doesn't perform like Chevrolet says it should, and it is the cause of many water cooling system problems. He recommends changing the ext. Life coolant every other year just like regular coolant, and judging from the look of the old coolant, I believe him! August update: I am now facing a transmission rebuild that the transmission man says is "typical" of these Ventures due to a mfg. Defect causing the transmission oil pressure to drop and kick the oil pump into high pressure mode forcing fluid through the system at such high pressure that every time it shifts, it feels like the transmission will jerk itself loose from the vehicle.

We have a 1999 Chevrolet Venture that we purchased in Dec. 2001. We did not purchase a warranty. A couple of weeks after the purchase the "check coolant" light came on and stayed on. We had to keep adding coolant. I do not work on cars and had a very sick wife, so the light was a minor stress at the time. I'd taken the car to get looked at and they said "the coolant is leaking into the engine, and the engine is going" well for a car with just over 23,825 miles on it, I was very steamed. It lasted till 47,359 miles and my wife was stranded on the road. The car was towed and sat at the chevy dealership from sept. 9th till Dec. 12th 2002. While still paying $437. 00 a month payment. We had a used engine put in it by the chevy dealership which had 20,000 less miles on it, and today has 74,000 miles on it. We paid $2,400 for this used engine. I just found out that the O2 sensor just went out on us. But if there is a defective engine or similar parts on it, is this going to happen again- just a matter of time?.