Oil viscosity questions

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Hello BITOGers! Long time lurker, new member.
So I’ve been wondering for a while but haven’t found a good answer. Many people believe that “thicker” viscosity oils protect better. Well with most if not all engines having an oil pump pressure relief valve, wouldn’t the best oil viscosity be as thin as possible to yet still hit that relieve valve pressure spec when hot?

Example: my 2017 Silverado calls for 0W-20. It has a relief valve pressure spec of ~40 until 3500rpm, when it then hits a second stage of flow where it ramps up 60+. I frequently tow 5K+ LBs in the hot summer months and it pretty much always hits that ~40 psi spec before 3500 rpm. In my mind, this is a good viscosity for this engine. What’re yalls thoughts?
 
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The engineers know best. Whatever your manual calls for in the temperature it will be operated under the service category (Regular, Heavy Duty etc.) is what you should use.

That said a quality 0w20 if that is what the manual calls for, is suitable. You can verify this with a UOA to be sure!
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FWIW there are others on here with Ram trucks doing towing with 20wts in the crank case.
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Oil pump relief valve pressure is never a parameter in determining suitable oil grade use or lubricant performance.
It's about engine system protection , say preventing filter bursting.
 
Originally Posted By: StevieC
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to BITOG!

The engineers know best. Whatever your manual calls for in the temperature it will be operated under the service category (Regular, Heavy Duty etc.) is what you should use.

That said a quality 0w20 if that is what the manual calls for, is suitable. You can verify this with a UOA to be sure!
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FWIW there are others on here with Ram trucks doing towing with 20wts in the crank case.
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Thanks for the response! I have no doubt 20wts can protect my engine more than adequately. Not saying I would trust them for long drain intervals though. I’ve been running about 4,000 mile intervals with 0w-20 M1 AFE. I know it’s probably way too short, but probably 50% or more of those miles are towing miles so I figured might as well be safe. Will do a UOA now that I have about 13k on the truck and have performed my 4th change. (One of which was at 500 miles).

Switched over to Penzoil Platinum seeing as it was on sale and my engine is actually noticeably quieter at idle. Had the ever so slightest tick on M1 that I attributed to DI noises.
 
Originally Posted By: Bxnanaz
Thanks for the response! I have no doubt 20wts can protect my engine more than adequately. Not saying I would trust them for long drain intervals though. I’ve been running about 4,000 mile intervals with 0w-20 M1 AFE. I know it’s probably way too short, but probably 50% or more of those miles are towing miles so I figured might as well be safe. Will do a UOA now that I have about 13k on the truck and have performed my 4th change. (One of which was at 500 miles).

The safety of a long drain interval isn't really related to the grade. That wouldn't be my concern.
 
Forget UOA. If you want a little more high load safety margin (I don't know what you mean by protection) substitute a qt or 2 on the next oil change with a 30 grade.

Oil pressure just puts oil into the bearings the pressure doesn't float the shaft, that's the inherent working viscosity of the fluid. So Oil grade e.g: 20, 30, 40 provides your loading safety margin.

BTW, There is no 20wt or 30wt or "weight". Its a misuse of terminology.
 
It specs 0W-20 mainly because of fuel economy regulations.
If you use 0W-30, 5W-30 absolutely nothing bad will happen, 0W-20 will be fine though aswell, and personally until the warranty runs out i would run 0W-20, because that way if anything went wrong with the engine and they saw you didn't use their specified oil, that may void the warranty.
 
Originally Posted By: FordCapriDriver
It specs 0W-20 mainly because of fuel economy regulations.
If you use 0W-30, 5W-30 absolutely nothing bad will happen, 0W-20 will be fine though aswell, and personally until the warranty runs out i would run 0W-20, because that way if anything went wrong with the engine and they saw you didn't use their specified oil, that may void the warranty.


Warranty is the main reason I’m gonna keep running 0w-20. UOAs will help me determine what I run after warranty
 
Originally Posted By: zeng
Oil pump relief valve pressure is never a parameter in determining suitable oil grade use or lubricant performance.


Correct.

Hydrodynamic protection between two metal surfaces is the REAL criteria.

Metal making contact with metal = no bueno
 
My thought process was if the relief valve is set a X pressure, and a 0W-20 hits X pressure, why go any “thicker”.? Obviously I was wrong on that.
 
Pressure doesn't equate with protection. Flow has more to do with it. That's not to say you don't need some pressure but it's not the be all end all.
 
Don't! UOA is junk science.

Throw some ten dubbya thirty in there b4 its too late, pardner.

Like I say maybe 1 or 2 qts of the mix.

Dealer doesn't have a clue what oil is in there. And 1-2 cst gooey-er oil isn't going to ding ANY alarms.

Don be a fairy trucker 'fraid of the big bad mean dealer. I'm shaken in my boots!

You motor would be proud to be in a Z28 or Vette in the 70's as a High Output option. It putting down some powah! It neeeeds some vis coz city!

Yeah, good luck on that 20 grade. He He.
 
My thoughts are I have that motor and the 0w20 bugs me a bit … the 8 quarts gives me mixed emotions … might hold up to DI better than 6 quarts ~ but 6 quarts of 5w30 is pretty cheap and good for south Texas use …
 
Originally Posted By: StevieC
Pressure doesn't equate with protection. Flow has more to do with it. That's not to say you don't need some pressure but it's not the be all end all.

Please explain? In a technical way I mean.
 
Originally Posted By: Bxnanaz
Warranty is the main reason I’m gonna keep running 0w-20. UOAs will help me determine what I run after warranty

Just so you know, as far as anyone has ever shown there's no indication that oil grade is somehow related to warranty. It is often repeated here but we had a thread about it a while back and no one could provide any proof that it was true. Your owner's manual doesn't say that it is a warranty item, does it? Oil grade is a recommendation, not a requirement.
 
Originally Posted By: kschachn
Originally Posted By: Bxnanaz
Warranty is the main reason I’m gonna keep running 0w-20. UOAs will help me determine what I run after warranty

Just so you know, as far as anyone has ever shown there's no indication that oil grade is somehow related to warranty. It is often repeated here but we had a thread about it a while back and no one could provide any proof that it was true. Your owner's manual doesn't say that it is a warranty item, does it? Oil grade is a recommendation, not a requirement.

I’ll definitely take a look at the manual when I get home. If that’s the case, I’ll most likely switch to a 5w-30 on my next fill.
 
Originally Posted By: kschachn
Originally Posted By: StevieC
Pressure doesn't equate with protection. Flow has more to do with it. That's not to say you don't need some pressure but it's not the be all end all.

Please explain? In a technical way I mean.


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Can folks spot at least a couple very hard working parts on this chart not getting a big share of flow

 
I have a little concern with 0w20 I was using PP and M1 AFe for my Malibu and ever time I check the level around 2500mi mark im a notch down . Compared to 5w30 where no loss at all . I have the 2.5ecotec the motor revs a little. This motor has the same block as the LTZ 2.0t which requires 5w30 . I looked up part numbers between the two motors it has the same timing chain , oil pump and filter . The car is outta warranty next month . What you guys think??
 
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