Everyone knows adding boost to your car is a fun time. More power is always a good thing, but it doesn't come free of charge. There are several factors you have to consider when slapping a turbocharger or a supercharger onto your engine, like how the rest of the powertrain will cope with the extra torque. Boost plays a major factor in what kind of oil you should be running, too.
The Motor Oil Geek on YouTube recently published a video showing what happens to an engine's oil when boost is added to the system, and the results are fascinating. Using an LS-based V-8 built for drag racing, the engine was run on a dyno both with and without boost. The oil was then run through an analysis to see how it handled all that added pressure.
The oil in the naturally aspirated motor did well to maintain a healthy viscosity over its dyno runs, maintaining the correct amount of additives. Once the supercharger is added, though, things get concerning. Adding boost means pushing more fuel into the engine, which means more fuel ends up in the oil. That dilutes things, driving down viscosity. That means the engine isn't running the correct weight anymore, even though the oil you're putting in is the same.
The result of incorrect viscosity is, of course, increased wear and tear on the engine. The analysis shows big increases in the levels of wear metals like iron and copper present in the oil used to run the boosted V-8. Over an extended running time, this engine would fail far before its naturally aspirated equivalent simply because the oil wasn't meant to cope with the boost.
Take this as a lesson, and be sure to check whether your oil can cope with some extra boost before you slap a turbo to your engine.
