Need advice on 99

I'm considering buying a 99 Malibu with a 3.1 V-6 with about 98K on it for my daughter. I know that that the 3.1s had a lot of problems with leaking intake manifold gaskets, but don't know the specifics.

(1) What year engines had these problems?
(2) At what mileage do the leaks usually start to occur?
(3) If I see moisture around and below the thermostat housing, does that indicate an intake leak?
(4) How much does it cost to replace an intake gasket, and will Chevy still work with a consumer on a car with this many miles?
(5) If this engine is not leaking at the intake now, can I do anything to prevent a leak in the future, such as pouring a sealing product into the radiator, etc.?
(6) If this engine hasn't developed a leak up to this point and with this much mileage, what is the likelihood it will develop one in the future?
(7) What is the likelihood the headgasket is blown as well if a leaky intake gasket is found?

Thanks in advance for any advice you can provide.

(Q1) What year engines had these problems?
A1: I believe all, 1997 through 2003, have this issue across all GM models.

(Q2) At what mileage do the leaks usually start to occur?
A2: Most people begin to see fluid by 85,000 but almost always by 120,000. Mine was completly shot at 133,000.

(Q3) If I see moisture around and below the thermostat housing, does that indicate an intake leak?
A3: More than likely you will either see fluid on top of the transmission housing on the driver's side, or puddled near the back of the power steering pump on the passengers side.

(Q4) How much does it cost to replace an intake gasket, and will Chevy still work with a consumer on a car with this many miles?
A4: Most people do not get anything from Chevy, especially if you didn't buy the car new. Taking the car to a Chevy dealer, walking in the door and saying "replace the Lower Intake Manifold Gaskets" will run about $600 - $700. You will want to have them replace the Water Pump, Thermostat, Cam Position Sensor, Fuel Rail o-ring, Coolant crossover o-ring and Accessory belt at the same time though, raising the price to about $800 - $900. If you are mechanically inclined (and have a spare Saturday) it will cost about $400 to do everything, and take you about 8-12 hours.

(Q5) If this engine is not leaking at the intake now, can I do anything to prevent a leak in the future, such as pouring a sealing product into the radiator, etc.?
A5: No. The damage has already been done.

(Q6) If this engine hasn't developed a leak up to this point and with this much mileage, what is the likelihood it will develop one in the future?
A6: 100%. The coolant eats away at the plastic surrounding the gasket. The replacement gasket has been re-designed though, and if replaced will likely not fail again.

(Q7) What is the likelihood the headgasket is blown as well if a leaky intake gasket is found?
A7: From talk on this board, I would say about 1:10. Most people are able to catch it before coolant ever makes it through the engine block.


Overall, this issue is a real pain in the rear, but if you consider what will be replaced for under $1,000 it is not horrible.

Thanks very much!