Mostly correct, however, thinner oils are far better for short trips than thicker oils.

Since xW-20 oils came on the market over 20 years ago I've yet to see any compelling evidence suggesting accelerated engine wear for normal day-to-day driving. Yes, if you are towing, or spend lots of time on a race track, the heavier oil may well provide a modest amount of added protection, but for daily driver chores, no. That said, I do not expect you to believe me, however, if you go over to BITOG and look at the literally thousands of xW-20 UOAs from Black Stone and other labs, you will find virtually zero evidence to support your claim of "...not good for engine wear."

 

Here is an example fore you: most modern engines have low tension piston rings(thanks to CAFE), on top of that cold engines are running rich. Traveling short trips with increased blow by adn there will be oil dilution. "Oil dilution" will lower the oil’s viscosity and it will lose lubricating properties and film strength is reduced.
I am sorry, but I will have to disagree. The only positive aspect of thinner oil I can think of is that it will heat up quicklier compared to the thicker oil..

 

Is not that only a problem for direct injection cars?

 

Please provide one supporting reference for your claims.

 

Yes this problem is more common with GDI and FI. It depends on engine, piston design, compression rings etc. Blow by will clog oil retunr rings. Look what happened to j37 engines when they changed piston design with new "low tension rings"

 

The J37 has this compounded with higher side loads due to the way the stroke and bore is vs J35/32/30

Use a good oil and filter and don't use too long of extended intervals without oil analysis to show its ok to do so.

 

When I went thicker in my 2012 Acura TL I had decreased gas milage. I could feel the thickness on the lips during acceleration. Also when u go thicker and the oil gets dirty - I presume it gets even thicker. Clogging passage ways.

thankfully Acura came through with a no cost engine rebuild. And now instead of using thicker oil to keep oil consumption at bay, I don’t have to. I simply try not to idle a lot, I also do an em take cleaning with STP PRO SERIES INTAKE VALVE CLEANER every oil change also adding liquimoly mos2 - and she purrs like a kitten. Consistently the engine drives like the day she came from the factory. As the oil degrades even still no degradation in performance on my opinion.

but in a nutshell it’s the oil you use, how you drive not necessarily the weight. But actually chose 520 for a reason for my car. So I’m gonna trust them.

 

Man, motor oil debates are always one of those things. I am inclined to dismiss the people who always swear by higher viscosities because their evidence is rarely, if ever, scientific or data-driven, and they seemingly just want to blame the EPA and CAFE standards (which I do personally disagree with because they were designed in an illogical way). But at the same time, to me there has been plenty of evidence that companies in the US, especially domestic ones, have cared far less about reliability. From my understanding, the J37A engine in Japan is used in the Honda Legend (KB2), which recommends 5W-30. I know there are many examples like that for Subarus and a handful of German cars. Companies in the US have become far less consumer friendly, and I wouldn't put it past most of them to sacrifice reliability so they can hit a certain price point, show a lower cost of ownership, or hit certain fuel economies. I always try to stay within the manufacturer's spec, but if I ever decide to properly track my car, I think I am going to switch to a high-quality 5W-30, at least for the session. The more reading I do about motor oil, the less confident I feel about what anyone says. Maybe it's just because the test results are true to real life, but they only apply to a small portion of motorists, so there is maybe less evidence for 5w-20 being as effective in heavy-duty vehicles under moderate to high stress loads. But then again, I have my doubts because it seems like there are always 100 different things that cause problems in those engines, all of which could affect each other. One thing is for sure, manufacturers are doing a terrible job of convincing people to listen to them.