I've read many times about the constant problems with the manifold gaskets on the 3800 motors, but my question is with the 3.1 litre motors. My In Laws have a 2001 Buik Century with just over 120,000 kilometers on it. Were these motors also having the same problems with the gaskets and or manifolds?

The LIM gaskets at the least, are an issue I believe. I've heard them to be very leaky motors, but STILL very reliable.

I had the 3100 in my old Cutlass, bought it at 48,000 miles, drove it hard often, to 65,000 in a short time, with no issues at all.

Yes, the 3100 and 3400 have LIM gasket issues. The UIM are aluminum with both engines.

My mom had to have her leaking LIM gaskets replaced on her 03 Alero (3400 engine). The car only had 38,000 miles. GM paid for all of the repair except $100 since it was JUST out of warranty.

I was at my in-laws again and the conversation came up again about me doing there intake manifold gaskets on there 2001 Century 3.1. I assume all part can be purchase without going through the dealer?