Chevrolet L36

The 3800 Series II — GM's 90° pushrod 3.8, 205 hp and 312 N·m, in the LeSabre, Park Avenue, Impala, Monte Carlo, Bonneville and the Australian Commodore. One of the most numerous engines ever fitted to a car, and a large part of why an American V6 of that decade is usually this one.

Its own distinctive failure is the plastic upper intake manifold cracking around the EGR passage, which the later revision corrected — so which manifold a car has matters more than its mileage. GM also recalled 1.5 million vehicles in 2009 for oil leaking under the valve cover gaskets onto hot exhaust, a fire risk rather than a running fault.

The supercharged version of the same engine is the L67, with an Eaton M90, lower compression and different pistons: 240 hp. A Series II that has been supercharged from the factory is not this engine with a blower bolted on.

The fault this engine is known for is the intake manifold gasket, and it is a GM-wide one: the 1995–2004 cars with the 3.1, 3.4, 3.8 and 4.3 share a composite gasket that the metal either side of it works loose as the engine heats and cools, until coolant finds its way out — or worse, in. Coolant in the oil on one of these is the gasket until proven otherwise, and the revised gasket and thread-locked bolts are the repair rather than a head job.

Dex-Cool is blamed for it in most retellings. GM investigated and concluded the coolant was not the mechanism, and the honest reading is that the gasket fails on its own and the coolant then makes a visible mess of what it finds — which matters, because replacing the coolant and not the gasket fixes nothing.