Problem Reports

Intake Manifold gasket failed, developed a leak - as indicated by coolant pooling on manifold. This leak was very slow, and I had no driveability issues, but finally took care of it.
If this happens to you - have the mechanic check your oil pump as well, since the gasket material can degrade into your engine coolant and "sludge" up the pump, screens, etc. in your oil system...I am dealing with this right now.

125K miles, drivability ok but cross contamination of oil into coolant

had to replace manifold gaskets - TWICE. now at 197,000 miles and make sure you only put in 4.5 quarts when you change the oil seems to have worked the last 40,000 miles

Found oil in coolant. Thought it was going to be head gaskets. Researched it on the web and many sites pointed to lower intake manifold gaskets. Did the job myself and as expected, gaskets were shot.

Was loosing coolant slowly, every few days but couldn't find a leak. Took to repair shop who showed me leak in front of rear cylinder bank where the upper manifold gasket was leaking. I got All-Data repair info and fixed myself saving hundreds of dollars. Now my water pump has developed a leak due to my changing coolant from DexCool to green after flushing it well. A Firestone dealer told me the DexCool does contain better lubricating oils for the water pump and that once you go to green normal extended life coolant the pump may well leak within 9-12 months, exactly what happened.