how come so many people change to a thicker oil or think there oil is too thin?

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The more viscous oil may contain VM and base oils and else. Therefore such upgrade in viscosity grade can mean weaknesses, problems, less protection (and also mean reduced MOFT btw). Against the bingo lessons the insinuated upgrade can read like a clear downgrade and the funniest 1/8W-12.3456 can beat the 5W-50 in MOFT. This of course mazda3lover himself should do: start to read! Instead of watching bingo until MOFT is stripped of all meaning.

Ignored.
 
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In my wife’s 2015 Altima I did a 3x drain and fill with Castrol trans max cvt around the 49K mile mark. Has a little over 60K On it now and no problems and cvt runs fine. Planning on doing a single drain/fill every 25-30K from here on out.

My 2017 accord sport did the same thing around the 30K mile mark with Amsoil cvt fluid.
 
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25,897
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Much too coarse to be of much value answering his quest; too loose a connex with viscosity grades and not even "HTHS" will help out instead, too far off actually in several areas and regards. This depicts an often completely wrong track as if it were to be followed.

The more robotic this sad activism becomes, the more urgently it needs to get treated – which probably makes for the most precise first response possible in this thread. It came that way. Sad narratives superspreaded in basic disinterest, ignorance, exaggeration, mission, misheard lyrics Karaoke & group dynamics et al.
Nope ... what I said is the basic backbone of Tribology and holds true. The oil viscosity factor is directly correlated to the thickness of the oil film between moving parts. It's been that way ever since a man discovered that an oil film keeps parts from rubbing excessively on each other.
 
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25,897
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The more viscous oil may contain VM and base oils and else. Therefore such upgrade in viscosity grade can mean weaknesses, problems, less protection (and also mean reduced MOFT btw). Against the bingo lessons the insinuated upgrade can read like a clear downgrade and the funniest 1/8W-12.3456 can beat the 5W-50 in MOFT. This of course mazda3lover himself should do: start to read! Instead of watching bingo until MOFT is stripped of all meaning.
Got a source to show that an oil magnitudes thinner (your "1/8W-12.3456 can beat the 5W-50" example) has a higher MOFT in use and a higher KV100 and HTHS than one much thicker? When I look at oil manufacture's oil product spec sheets there's a very good correlation between oil grade and KV40, kV100, HTHS ... all of which contribute to higher MOFT in use. There might be a rare "outlier" in the mix, but that's very rare.
 
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Of course it is related, but it doesn't easily rule. Read again.
It rules more than other factors in keeping parts separated. What do you think rules more than viscosity in keeping parts separated with all other factors held constant?
 
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A 1/8W-12.3456 with the HTHS of a 0W-20 will be in the league of a 5W-50 with HTHS 4 1/2 or beat it in MOFT for a cylinder above idle or for a trochoid or a timing chain. There's not one MOFT throughout an engine, right?
These extremes were used to make clear what the bingo is worth when choosing civil 0W-30 or 5W-30 instead of 0W-20 for the Mazda. And that's just the MOFT theme. No overall protection yet. Or winter suitability beyond pumpability and crankability...
 
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I can't say it's any better to run heavier weight but, I do. I started using 10w40 when I bought my first car in 1977, it has served me well so I just stick with it. I've heard some engines running lighter weights that seem to have more engine noise. I like an engine that runs quietly I never hear anything in my engine that I think could be related to the oil viscosity. My old daily driver an '88 Escort had 518K miles on it and was about 23-24 years old when I quit using it. There was no knocking and the compression was still 145-155 PSI across all cylinders. I've had engines with 200-300K miles and still going when I got rid of them. Two of my current cars have in access of 200K miles both use about 1/2 quart between 5K mile OCI's. The owners manual in my '16 Versa says use anything from 5w30-10w40. I guess having about 10-12 cases of 10w40 in my garage that I bought years ago is as good a reason as any to continue using it. I used to run 20w50 in my motorcycle that was spec'd for 10w40. I felt better about a heavier weight oil in an air cooled engine that was often run in 95-105*F weather.
 
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A 1/8W-12.3456 with the HTHS of a 0W-20 will be in the league of a 5W-50 with HTHS 4 1/2 or beat it in MOFT for a cylinder above idle or for a trochoid or a timing chain.
There is no 0W-20 oil "in the league of 5W-50" in terms of HTHS. And any oil with a much lower HTHS viscosity isn't going to produce a MOFT as large as a much thicker oil with much higer HTHS at the same use temperature. Show me one example please.

There's not one MOFT throughout an engine, right?
True ... but the focus of the discussion is that MOFT will increase between parts as a function of viscosity when all other factors are held constant. And the oil viscosity is what produces the separation between moving parts - lower viscosity equals less MOFT with all other factors held constant. Been that way ever since the start of the study of machine lubrication 100+ years ago.
 
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I'll try to make one 1/8W-12.3456 up :)

But it shouldn't even be necessary. Look, again that's not what I've written down, I didn't make the 2.6 = 4.5 in terms of HTHS. What I'm referring to is a 5W-50's "BOV150" around 2.6. The fiction of a 1/8W-12.3456 (rather empty and newtonian, of high intrinsic VI and density, maybe primarily OSP, ester...) with the HTHS-V of 2.6 at the same time has the BOV150 around 2.6. Let it make a little more MOFT from the same BOV150 because racecar advanced base oil and there you are.

You didn't hold any factors constant, you just pushed mazda3lover onto the silly tracks as you always love to do. If people are seen as trolling or just annoying, show them a link or two and tell them to read up or whatever. But stop reproducing what's completely worthless – in probably 10000 hits via forum search for "MOFT" right now. It ain't nearly in the grades and not even in HTHS, not even plain bare naked MOFT.
 
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Higher viscosity = a larger MOFT = larger gap between moving parts = less wear and more headroom from metal-to-metal contact occurring. Trilogy 101.

I can't believe this post got like 6 likes.

Can someone explain to me how a crankshaft and a bearing or a piston and a cylinder wall, which are machined with a specified clearance between them, has a larger clearance by using thicker oil? It doesn't. It simply cannot.

That film of oil can be stronger in the space provided, but the space itself cannot physically be larger.

And I believe you meant tribology.
 
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I'll try to make one 1/8W-12.3456 up :)

But it shouldn't even be necessary. Look, again that's not what I've written down, didn't make the 2.6 = 4.5 in terms of HTHS. What I'm referring to is a 5W-50's "BOV150" like 2.6. The fiction of a 1/8W-12.3456 (rather empty and newtonian, of high intrinsic VI and density, maybe primarily OSP, ester...) with the HTHS-V of 2.6 at the same time has the BOV150 around 2.6. Let it make a little more MOFT from the same BOV150 because racecar advanced base oil and there you are.

You didn't hold any factors constant, you just pushed mazda3lover onto the silly tracks as you always love to do. If people are seen as trolling or just annoying, show them a link or two and tell them to read up or whatever. But stop reproducing what's completely worthless – in probably 10000 hits via forum search for "MOFT" right now. It ain't nearly in the grades and not even in HTHS.
I said more that once "with all other factors held constant". It really shouldn't have to be said because many of these discussions are focused and based on when only one factor is changed.

Nothing silly about the fact that oil viscosity, regardless of how the finished formulation results in the HTHSV, results in higher MOFT and greater parts separation. If you think that's worthless, them maybe you need to bone up some more on how viscosity plays a role in moving parts separation.

If you don't think oil viscosity is reponsible for the thickness of the oil film between moving parts (MOFT), then I'd like to know what you believe is responsible - with all other factors held constant of course.
 
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I can't believe this post got like 6 likes.

Can someone explain to me how a crankshaft and a bearing or a piston and a cylinder wall, which are machined with a specified clearance between them, has a larger clearance by using thicker oil? It doesn't. It simply cannot.

That film of oil can be stronger in the space provided, but the space itself cannot physically be larger.

And I believe you meant tribology.
You don't seem to understand the relationship between oil viscosity, relative parts speed and the resulting MOFT between the fixed parts clearances which keep them from rubbing on each other and causing wear. Journal bearings ride differently in their fixed clearance depending on the oil viscosity and bearing speed. If the oil is too thin, and/or the speed too slow, the MOFT can go to zero and metal-to-metal contact will start to happen.
 
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You don't seem to understand the relationship between oil viscosity, relative parts speed and the resulting MOFT between the fixed parts clearances which keep them from rubbing on each other and causing wear.

That's not what you said before, you said the gap got larger. So which is it?
 
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Jimmy, the pistons or rotors arent supposed to get in much touch with the walls, only rings and seals are. The oil to a degree will inform those about ride height over wall. To protect something from scuffing we'd look in the direction of elasto-hydrodynamic lubrication, tribology. Insofar he's not wrong.
 
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The one I quoted earlier. Post #29.

I said: Higher viscosity = a larger MOFT = larger gap between moving parts = less wear and more headroom from metal-to-metal contact occurring. Trilogy 101.

You read it wrong. "Larger gap between moving parts" means a larger MOFT between moving parts. If you have more MOFT you have a larger "gap" between moving parts within their fixed clearance. Seems many here got what I was saying.
 
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