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0W-20 vs 0W-40 Fully Synthetic


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Hey guys, so I know on the oil cap of my 2017 Sierra with the 6.2 it shows 0W-20.

 

I'm no oil expert, but was thinking of doing my first oil change at 1500 miles (which I usually do on all my new cars/trucks, just after break in) with 0W-40

 

I have a case of 0W-40 Pennzoil Ultra Platinum left over from my Hellcat. This was the SRT recommended oil for the Hellcat's. Clearly it must be a great oil for it to be the one they use and recommend.

 

Does anybody here that is well versed in oil know of a reason I shouldn't use the 0W-40 over the 0W-20 oil?

The 0W-40 must be rated and good for higher engine heat with less break down than the 0W-20 correct?

 

Thanks

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Hey guys, so I know on the oil cap of my 2017 Sierra with the 6.2 it shows 0W-20.

 

I'm no oil expert, but was thinking of doing my first oil change at 1500 miles (which I usually do on all my new cars/trucks, just after break in) with 0W-40

 

I have a case of 0W-40 Pennzoil Ultra Platinum left over from my Hellcat. This was the SRT recommended oil for the Hellcat's. Clearly it must be a great oil for it to be the one they use and recommend.

 

Does anybody here that is well versed in oil know of a reason I shouldn't use the 0W-40 over the 0W-20 oil?

The 0W-40 must be rated and good for higher engine heat with less break down than the 0W-20 correct?

 

Thanks

Advanced Oiling System

 

The oiling system incorporates a new variable displacement two-stage vane-type oil pump that enables more efficient oil delivery, based on the engine’s operating conditions. Its dual-pressure control enables operation at a very efficient oil pressure at lower rpm, and then delivers higher pressure at higher engine speeds.

 

An oil control solenoid valve, controlled by the Engine Control Module (ECM), mounted to the oil pump provides two-stage functionality. The oil pump is mounted on the front of the engine block and driven directly by the crankshaft sprocket. The pump rotor and vanes rotate and draw oil from the oil pan sump through a pick-up screen and pipe. The oil is pressurized as it passes through the pump and is sent through the engine block lower oil gallery.

 

Pressurized oil is directed through the engine block lower oil gallery to the full-flow oil filter and then to the upper main oil galleries and the valve lifter oil manifold assembly.

 

An oil passage at camshaft bearing location permits oil flow into the center of the camshaft. Oil enters the camshaft, exiting at the front and into the camshaft position (CMP) actuator solenoid valve. The CMP valve spool position is controlled by the ECM and CMP magnet. When commanded by the ECM, the CMP magnet repositions the CMP actuator solenoid valve spool directing pressurized oil into the CMP actuator to control valve timing.

 

dexos 1™ Engine Oil

 

TIP: Failure to use the recommended engine oil and correct viscosity or its equivalent can result in engine damage not covered by the vehicle warranty.

 

The dexos1 specification was uniquely designed to complement the exacting requirements of GM’s advanced engine technology. The specification has gone through an extensive developmental and testing process. Only those oils displaying the dexos1 trademark and a registered trademark logo on the front label of the container meet the demanding performance requirements and stringent quality standards set forth in the dexos1 specification.

 

SAE 5W-30 is the required viscosity grade for the 4.3L engine.

 

SAE 0W-20 is the required viscosity grade for the 5.3L and 6.2L engines.

 

DO NOT use other viscosity grade oils such as SAE 10W-30, 10W-40, or 20W-50.

 

The engine oil with filter capacity has increased significantly from model year 2013 to model year 2014.

 

This also includes 2017 models as nothing has changed.

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Since they're both full synthetic they will break down at the same rate. There's a reason GM says 0W-20. It might be for better gas mileage, but I wouldn't risk running 0W-40. I believe the oil also help operate the AFM so maybe that's a reason for 0W-20. So all in all, I wouldn't risk running the wrong viscosity just because you have a jug laying around. They both will be the same viscosity when cold, but as they worm up the 0W-40 will be thicker. If that 0W-40 jug is unopened I would just sell it or give it to someone that uses that viscosity.

Edited by SouthernSilveradoGuy85
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0w20. Between AFM, the variable displacement oil pump, more aggressive VVT and CAFE requirements, they switched to it. Run what it calls for. Different oiling requirements for similar engines. The LT1 and LT4 run 5w30 but their performance requirements set by GM require the use of 5w30.

 

Just like the HEMI. 5.7 trucks and cars run 0w20, but the performance applications (6.2 HC engine) run 0w40.

Edited by 15HDriver
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I would run the specified oil. Will the 0w-40 hurt, maybe not but why take a chance. As stated above the engine was designed to run on 0w-20. Running a thicker oil can effect the AFM and possibly even cause issues with the VD pump.

 

 

I'm no engineer but if they programed the ECM to control the oil pump according to it's state of flow or pressure, then if a thicker oil is ran it might adjust it to operate differently than designed and could cause issues, like over pressurizing and possibly seal issues? I don't know but it is something to consider. This isn't the engines of old with a simple oiling system that we grew up around.

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Never deviate from the factory viscosity, not these days. If it says 20 then use 20. You could probably get away with 5w20 if you're in the warmer climates, but that's it.

 

Long term use of 40 weight will almost certainly harm an engine designed for 20 weight nowadays.

 

I used to work at a Ford dealer and when the Crown Vics switched to the 4.6 engine, it specified 5w30. Many folks just ignored that and continued using 10 or 15w40....and in a few years, they had oil burners. What was really funny was all the folks who still didn't believe that was the problem.

I've literally seen running problems (rough idle, etc) caused by simply having the wrong oil in the engine.

 

So yeah, don't change it. Keep what GM says to in there.

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I didn't read the whole thread. The 4.6 fords had long timing chains that had tensioners that were oil sensitive. If you use the wrong oil and weight you would prematurely wear out the chain, among other oil related problems. I came from an area where the thicker the oil the better, and the cooler the engine temp the better. All wrong these days.

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I didn't read the whole thread. The 4.6 fords had long timing chains that had tensioners that were oil sensitive. If you use the wrong oil and weight you would prematurely wear out the chain, among other oil related problems. I came from an area where the thicker the oil the better, and the cooler the engine temp the better. All wrong these days.

Same with the 3.6 engines like what was in our 2011 Acadia, since they are a DOH cam with long timing chains. The oil is also a hydraulic oil and plays part on the VVT on them. So you need to run the correct weight oil.

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Has the 0W20 been the spec oil in the K2XX 5.3s? A neighbour who is a older gentleman (in his 70s) was commenting about the oil in his late model Chev pickup. He just picked up a '16. Like most people he was thinking that this new viscosity combination wasn't far off of water.

 

I feel a bit more comfortable knowing the 6.0 L still gets 5W30.

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  • 2 weeks later...

Has the 0W20 been the spec oil in the K2XX 5.3s? A neighbour who is a older gentleman (in his 70s) was commenting about the oil in his late model Chev pickup. He just picked up a '16. Like most people he was thinking that this new viscosity combination wasn't far off of water.

 

I feel a bit more comfortable knowing the 6.0 L still gets 5W30.

 

Yea 5.3 and 6.2 run 0w20, the 4.3 V6 and the L96 6.0 in the HD run 5w30.

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  • 3 weeks later...

I get the impression that the OP, and possibly some others, was misconstruing what an oil viscosity is. The number in front of the "w" is a winter flow rate, not a viscosity. The "w" stands for winter, not weight. A quick look at the SAE standards site will confirm this. The number after the "w" is the viscosity rating. Unless a engine was on it's last leg and really loosened up to the extreme, I wouldn't consider a 40w oil in them. A 30w, maybe in the right circumstances.

 

If it were me, I would opt for a 5w20 over a 0w20. 5w20 is rated to meet the cold crank simulator test flow rate requirements of the engine to -30c. Now that is pretty darn cold. If one lives in Fairbanks, AK or Destruction Bay, YT, then yeah, a 0w20 would be a good thing. For those of us that don't live in such extremes, a 5w20 would be better. Why? Because a 5w20 has a much lower NOACK (burn off vaporization rate) than a 0w20, and 5w20 requires fewer polymeric viscosity improvers which can shear under pressure. Both of these very important considerations given the VVT and AFM stuff going on in these engines. And a 0w20 and a 5w20 are the exact same kinematic viscosity at engine operating temps. And yes, there are a stack of 5w20 oil on the dexos1 list for those that worry about that. And I defy any dealer or OEM to be able to tell the difference. A regular oil sample analysis will not show it. A more extensive analysis could tell, but only on a virgin oil sample. On used oil, it is virtually impossible except for very costly lab analysis. At that point, it would be cheaper for the OEM to just replace the engine.

 

All of my gassers call for 5w30. I use 10w30 in them for the very same reasons I mentioned. 10w30 is rated to meet the cold crank simulator test flow rate of the engine to -25c, and that is extreme cold for my area except on very rare occasions. Again, the OEM would never be able to tell.

 

Haven't had an engine component failure in 45 years and over 5 million miles. Of course, most of those miles were commercial driving.

Edited by Cowpie
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I get the impression that the OP, and possibly some others, was misconstruing what an oil viscosity is. The number in front of the "w" is a winter flow rate, not a viscosity. The "w" stands for winter, not weight. A quick look at the SAE standards site will confirm this. The number after the "w" is the viscosity rating. Unless a engine was on it's last leg and really loosened up to the extreme, I wouldn't consider a 40w oil in them. A 30w, maybe in the right circumstances.

 

If it were me, I would opt for a 5w20 over a 0w20. 5w20 is rated to meet the cold crank simulator test flow rate requirements of the engine to -30c. Now that is pretty darn cold. If one lives in Fairbanks, AK or Destruction Bay, YT, then yeah, a 0w20 would be a good thing. For those of us that don't live in such extremes, a 5w20 would be better. Why? Because a 5w20 has a much lower NOACK (burn off vaporization rate) than a 0w20, and 5w20 requires fewer polymeric viscosity improvers which can shear under pressure. Both of these very important considerations given the VVT and AFM stuff going on in these engines. And a 0w20 and a 5w20 are the exact same kinematic viscosity at engine operating temps. And yes, there are a stack of 5w20 oil on the dexos1 list for those that worry about that. And I defy any dealer or OEM to be able to tell the difference. A regular oil sample analysis will not show it. A more extensive analysis could tell, but only on a virgin oil sample. On used oil, it is virtually impossible except for very costly lab analysis. At that point, it would be cheaper for the OEM to just replace the engine.

 

All of my gassers call for 5w30. I use 10w30 in them for the very same reasons I mentioned. 10w30 is rated to meet the cold crank simulator test flow rate of the engine to -25c, and that is extreme cold for my area except on very rare occasions. Again, the OEM would never be able to tell.

 

Haven't had an engine component failure in 45 years and over 5 million miles. Of course, most of those miles were commercial driving.

 

 

Thanks for your detailed reply.

I understand the "W" is for winter. The reason I asked others about the use of the 0W-40 over the 0W-20 is because I'm not technically versed in the differences in the make up of these two oils.

For years, it really didn't matter what oil you put in. Matter of fact, in owner's manuals they would tell you to use the weight/viscosity of oil that best matched the climates or driving conditions you lived in. If you lived in really cold climates they'd tell you to use 5w-30. You lived in hot climates you could use 10w-30 or even 20w-40.

For the past 5-10 years it seems auto makers are stating what oil to use, no matter the climates.

I don't live in an area that gets even into the teens. Usually we only have a couple days all winter long that even gets into the 20's.

So yes, 0W oil doesn't seem to be needed where I live and drive.

But wasn't sure if there was a true technical/engineering reason to not use the 0w-40 I had left over from my Hellcat in the Sierra 6.2

 

Clearly the 0w-40 oil for the Hellcat is much higher rated oil for an extremely high performance engine, so to me it seemed like, "well if it's what is used in a Hellcat, it surely overqualified for the Sierra."

But there may be a more technical/engineering reason to use the 0w-20 oil in the Sierra, that's why I asked.

If I'm not mistaken the 0w-40 would be a tiny bit thicker than the 0w-20 and that may not be the greatest for the Sierra engine?

 

But based on the responses it seems it's just best to stick to what they recommended in the 0W-20

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It is a balancing act really. Viscosity is not thickness of the oil but the measure of an oil's resistance to flow. Even a 50w oil, the molecules are much smaller than even the tightest clearances of modern engines. But, a engine has to have a balance of good flow thru critical areas, but not so fast that oil gets squeezed out too quickly in high pressure areas. Leaving gaps that are not properly lubricated. But not too slow that it cannot provide the other job of oil which is cooling and the increased temps in those tight areas causing heat related damage and oil shearing out of grade. Hence, the old days of just throwing anything in and getting tolerable results is pretty much over. Some variances are ok, but extremes can be bad.

 

A 0w20, the viscosity at operating temp is roughly 8.5 cSt at 100c. A 0w40 has a viscosity of roughly 14.8 cSt at 100c. It requires almost double the pressure to force it thru critical areas. That may be too much given the engine in question and what it is being used for. Obviously, in high RPM race situations, a 20w will not do the job properly. The temps and quick flow viscosity will cause spots of inadequate lubrication. A higher viscosity oil would perform better. But for the average user out on the street, that is not as critical of a situation.

Edited by Cowpie
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  • 1 year later...
On 12/19/2016 at 3:30 PM, newdude said:

0w20. Between AFM, the variable displacement oil pump, more aggressive VVT and CAFE requirements, they switched to it. Run what it calls for. Different oiling requirements for similar engines. The LT1 and LT4 run 5w30 but their performance requirements set by GM require the use of 5w30.

 

Just like the HEMI. 5.7 trucks and cars run 0w20, but the performance applications (6.2 HC engine) run 0w40.

The difference between the L86 (sierra 6.2L) and the lt1 is the intake manifold, location of water pump and tuning along with some exhaust changes,they only spec the truck for 0w20 because of the number of trucks they sell (+900,000 in 2017)vs the number of corvettes and camaros (less than 100,000 in 2017), the CAFE savings is what drives the decision to spec the new trucks for the 0w20 instead of staying with 5w30 of the last truck generation v8's. The L86 and LT1 both use the same oil pump and internals so if 5w30 was such a big issue their oils would have changed also. 

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