Give the 3.0T TFSI powering your 2018+ Audi S4 or S5 the extra layer of defense that it needs with the Mishimoto Direct Fit Baffled Oil Catch Can. Volkswagen and Audi were on the front lines of the direct injection revolution, which means they were also one of the first to implement a means to protect against blow-by gasses. While the factory AOS system does filter out some oil and fuel vapors, the harmful contaminants still make their way to the intake valves. The Mishimoto Direct-Fit Baffled Oil Catch Can Kit for your 2018+ Audi S4/S5 installs in line with the PCV system right after the factory separator for immediate protection of the intake components. Our catch can features a patent pending 2-port Compact Baffled Oil Catch Can with a 50-micron bronze filter and an internal baffle to better separate oil from the crankcase vapors. Our kit also includes a set of direct fit hoses for a simple installation, including two Mishimoto One-Way Performance Check Valves to prevent your catch can from becoming pressurized. In order to simplify servicing, our kit includes a petcock drain kit, so draining captured blow-by is a cinch. The Mishimoto 2018+ Audi B9 S4/S5 Direct Fit Catch Can Kit also includes the Mishimoto Lifetime Warranty for a worry-free installation. Our catch cans are different from most air-oil-separator (AOS) systems on a few levels. First, our catch cans are not heated. This means that all of the blow-by is able to condense in the can, including low-octane oil vapors and contaminated fuel vapors. Most AOS systems also drain the blow-by back into the oil pan, while our catch cans trap the blow-by and keep it out of the engine permanently. If you've seen what We've seen in the bottom of our catch cans, you won't want that draining back into your oil either.