Should I run 0W-20 or 5W-30 oil in my 2022+ WRX?

Subaru specifies 0W-20 full synthetic for the FA24, and capacity is roughly 4.8 quarts with the filter. If your car is stock and under warranty, run 0W-20 and stop reading - deviating from the specified grade gives a dealer an easy reason to question a claim, and the factory grade is genuinely adequate for how most VBs are used. The interesting part is why 0W-20 is specified at all. Thinner oil reduces internal drag, which helps fuel economy figures and cold-start emissions during testing, and those are meaningful regulatory pressures on a modern manufacturer. The commonly cited data point among enthusiasts is that the same FA24 turbo engine is specified with a heavier grade in some other markets, which suggests the choice is not purely about what the engine wants under load. So the argument for 5W-30 goes like this. A tuned VB makes considerably more heat and cylinder pressure than a stock one. Oil thins as it heats, and a heavier base grade retains more film strength at sustained high oil temperatures. On a car that sees track sessions, repeated hard pulls, or hot climates, that margin is worth having. The argument against is straightforward: it is not the specified grade, it may very slightly reduce fuel economy, and on a warranty-covered car it is an unnecessary talking point. A reasonable way to decide. Stock, daily driven, under warranty: 0W-20, no hesitation. Tuned, driven hard, out of warranty or willing to accept the warranty conversation: 5W-30 is a defensible and common choice. Track days specifically: this is where the heavier grade has the strongest case, because sustained oil temperature is the exact condition it addresses. What matters more than the grade. Use a quality full synthetic that meets the specification. Change it on the shorter end of the interval - Subaru's guidance is around 6,000 miles or 6 months, with a shorter interval for hard driving, short trips or extreme temperatures, and a tuned car sits squarely in the hard driving category. Monitor oil temperature if you have the means, because knowing your actual operating temperature settles this debate for your car better than any forum thread. And whichever you choose, do not switch grades hoping to fix a problem. If the engine is consuming oil, running hot, or showing knock, the oil grade is not the cause and changing it will only delay finding what is.