‘The new Toyota Corolla goes down to 0w8’: Mechanic reveals what type of oil newer cars really need—and why they’re so different

We know firsthand from talking with veteran repair supervisor Rich Poisson that the guy probably thinks about nothing but cars, 24/7. And you know what? Respect. We need more all-knowing professionals like that who are dedicated to their work and want to help all of us drive as safely and economically as possible.

So it’s no surprise that Poisson, co-owner of Brighton Auto YP in Chicago, recently posted a 4-minute monologue on TikTok about the different grades and viscosities of motor oil being used today, and why thinner blends rated at 0w8 or 0w16 are seen as more favorable for automakers.

Are thinner oils better?

The short answer: Thinner blends make engines run more easily than thicker blends, which means vehicles running those formulations get rated for higher mileage.

But Poisson cautions there’s a downside to using thinner oil.

“Oil has more than just one property. It's not just lubricating. It's also protecting the the engine, conditioning the seals, and also removing heat from areas that it can as much as possible. Thin oils do great with fuel economy and removing heat, but they have weak film thickness under more performance-based applications and more severe driving. Thicker oils don't remove heat as fast, but they have a better film thickness, which is to protect the rotating assembly better.”

Add this lesson to the list of things—like taxes, good mental health practices, and cooking—that I would've been better off learning in school, instead of how to calculate the length of sides of a right triangle.

Poisson notes that federal fuel economy standards for automakers have played a big role in the push toward lighter blends of motor oil, since gaining a few extra miles from every gallon of fuel means there’s fewer costly engineering and efficiency steps they have to work into their manufacturing processes. Of course, that could wind up costing owners in the end if there’s less protection happening around various engine parts.

“Overall, it's almost not bad to go thicker, but it's almost always bad to go thinner than what's recommended for the vehicle. Also, why would they tell us that we shouldn't go from a 5W20 to a 5W50 on that Mustang, theoretically, because if you put a thicker oil on your engine, it's going to mess with the timing and the VCT components and everything else, and you don't want that,” he said.

“A lot of times when people say stuff like that, they're full of it. The vehicle is going to be perfectly fine by running a thicker oil. Just monitor what's going on and keep a feel for how your vehicle is doing.”

Commenters on the clip had plenty of thoughts on Poisson’s view in support of thicker oils.

“I've run 5w30 in my 0w20 recommended car for 230,000 miles,” wrote one rebellious driver.

Then there’s this from a vocal fan of synthetic oils: “5w30 in everything that requires any 0w oils I been running dextrous 5w30 synthetic in all my cars.”

@fordbossme Replying to @howiemchowerton ♬ original sound - Rich

And there’s this from someone who seems to see things the same way Poisson does: “So run these thinner oils for better economy and rebuild the internals sooner. A lot can be said about longevity. Even 0w-20 seems a step backwards.”

The Daily Dot has reached out to Poisson via phone.

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