2001 Grand Prix GTP - Coolant and oil loss
My car has about 150,000 miles on it now.
For the past year or so I have been going
through at least two quarts of oil per oil
change. In addition, I have had to add
about a cup or so of antifreeze every 1000
or 2000 miles. It's enough that it is
This car has had Mobil 1 since I bought it
used in 2006 with 33000 miles. The lower
intake manifold was replaced by dealer in
2008 or 2009 with about 70,000 miles.
There are no noticeable leaks on the
ground. I am pretty handy but had the car
looked at by local shop and they put dye in
the oil. They could not find any leaks
whatsoever. I also brought it to the dealer
and they suggested we take the motor
apart with the assumption that the lower
intake manifold is bad. I opted not to do it
since they did not know for sure, and I
would be forced to replace the gaskets
since they can not be reused after
inspection. The car still runs strong but
where is all this oil and coolant going?
Don't know if this helps, but here's a suggestion. I own a 2003 Buick Regal, also a 3800, with a lot of miles. I was noticing an oil loss as well but couldn't find a trace of a leak, nor was it burning or in the coolant. Then, it came time for new engine and transmission mounts. When I removed the engine mount on the passenger side, there was a bout 2 cups of oil collected in the engine mount cradle. As it turns out, the leak was coming from the front of the oil pan, and leaking into the cradle. The cradle was collecting it, therefore no oil spots on the ground. And it's pretty much a straight drop into the cradle, so any dies would not even see a leak. All you have to do is remove your right front wheel, put your hand into the cradle that holds the engine mount and see if there is pooled oil. If so, there's your oil leak! As for the coolant, check the plastic elbows that go from the alternator bracket into the engine block on the right side of the car, just below the intake. These are very prone to leak, and their location makes it hard to detect.
I replaced the coolant elbows last year with Dorman metal ones. All visual areas are bone dry. As far as the oil goes, I will have to check the cradle when I get a chance..
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