Chevrolet 60° V6 (LB6 / LH0)

The 2.8 and 3.1 that came before the L82 / 3100 — GM's 60° pushrod V6 in its multi-port injected form, in the Beretta, Corsica, Lumina, Lumina APV and the W-body Regal.

They are the same architecture as the 3100 and 3400 and not the same engines. Heads, injection and management all changed at the 3100, so a part listed simply as 3.1 V6 covers two different generations. Establish the code before ordering anything, because the years overlap in the same body shells.

The family fault is the intake manifold gasket and it is GM-wide: a composite gasket that the metal either side works loose as the engine heats and cools, until coolant escapes — or gets into the oil. Coolant in the oil on one of these is the gasket until proven otherwise.

At this age the head gasket is the other candidate, and the two present similarly. What separates them is where the coolant goes: the intake gasket puts it into the lifter valley and the oil, the head gasket into a cylinder. A cooling system that holds pressure with the engine cold and loses it running is the head gasket; one that empties into the sump is the intake.