My 2012 Fiat Abarth manual specified 5w40, my 2022 Honda Civic SI manual specifies 0w20. The engines are almost the same displacement, 1.4 vs 1.5, and they're both turbocharged. The Fiat Abarth was port injected while the Honda SI is direct injected, so there's that.
Why the (seemingly) very different oil specifications? Is it the decade between the two cars that's the difference? Did the auto industry and engine needs "evolve" a lot in that time? Are these two engines are more different than I'm guessing they are?
The Fiat engine seemed to really like the 5w40, going strong at 70,000 miles when I got rid of it.
Thanks.
Just use 0w20 in your Honda.
Many people freak out when a manufacturer recommends 0w20, but there is no need to freak out. Only people in forums that actually know absolutely nothing about how oil viscosity really works in an engine complain and whine about manufacturers recommending thin oils.
Japanese car manufacturers (in America, Japan, and many other parts of the world) have been recommending 0w20 and 5w20 in their cars for about 20 years now. And, after 20 years of 5w20 and 0w20 being used in millions of Japanese cars all around the world, and these engines that ran on 5w20 and 0w20 are actually lasting a really really long time. Usually longer than engines that run on 5w30,40,50etc... It's a fact. Toyota also has been using 0w16 in Japan for almost 10 years (I believe it's about 10 years, not too sure though) way before we in the US started seeing 0w16, and they had zero issues. People overthink too much when it comes to oil viscosities. Just use what your manufacturer recommends, and you will be fine like all the other regular people that don't overthink and just use what's recommended.
So you hear all these random people on forums whining about: "0w20 is a scam, it's only for fuel economy, and my engine that uses 0w20 will stop working sooner because 0w20 is too thin".
0w20 does help with fuel economy, because it goes into bearings quicker, and also exits the bearing quicker. It's less drag, and less drag is always better, but thin oils also most importantly helps with providing better wear protection than thicker oils.
Using 0w20 on engines that recommend 5w20 and/or 5w30 is actually beneficial to a motor. 20 and 30 is interchangable. 30 and 40 is interchangable. Just don't go from a 50 weight to a 20 weight. That's too big of a jump. Anyhow, fast and high volume of oil flow is what determines how well an engine will be protected, NOT higher oil pressure. All modern passenger car engines have very tight clearances, not just the engines that use 0w20. Using thinner oils will give you lower oil pressure, but higher and faster oil flow in all RPM ranges. Using thicker oil will get you higher oil pressure, but the only reason why thicker oils give you higher oil pressure is because the oil is not flowing as fast as a thinner oil.
For example, just think about your crankshaft main bearings. The journal bearings are very very tight. It's tight on all engines, no matter what the "recommend" viscosity is from the factory. 0w20 is better than 30 or 40.
If you use a thin oil such as 0w20, the oil will flow into the bearing and form an oil film. The crankshaft is spinning very fast, and that aids in helping the oil form a good barrier all around and between the bearings. Spinning parts naturally draw oil in and form a film around itself in between what it's spinning on. Faster and higher volume of oil flow is critical, and 0w20 is the best for providing fast and high volume flow in cold and hot temperatures.
Use good quality 0w20 in your Honda like Mobil 1, Pennzoil, and Amsoil, and your engine will be good to go. Contrary to popular belief 0w20 won't make your engine wear faster. Contrary to popular belief, 0w20 will give you the best wear protection.