Background:
My wife drives a 99 Venture (3.4L) which had the intake manifold gaskets replaced this past December. The van was purchased used at 19k and has run Mobil 1 5W30 & GM oil filters since that point. I usually average 7500 miles between changes, but have gone to 10K a recently. The van does not use any oil. The van had the intake work done at 56K and it now has 65K on it. Prior to intake work, I noticed the coolant level dropping a little over a few months timeframe and probably added 1/2 gallon total. When I realized the intake was leaking, the oil had about 4k on it and the filler cap was "foamed" up. I changed the oil and took it to the dealer where they replaced the gaskets, etc. I then changed the oil again and ran it for about 1k and changed the oil again. Currently the oil has almost 7k on it and there are no other signs of coolant in the oil.
I realize the engine was probably damaged by the coolant in the oil. Did running the Mobil 1 synthetic help this situation at all? I plan to do an analysis at the next change, but that will be several months away. I asked GM for an extended warranty on the engine, but they would not budge. I did get them to pay for 1/2 of the cost of the repair, even though we were way of of warr.
Thanks,
Jim