0-20w oil

[steve45]

I generally agree, but it's important to understand the reasons why GM is specifying 0w-20 over 5w-30, 40, etc in order to understand what the pros/cons are of making a different choice. I don't know the answer with 100% certainty, but my understanding is that 0w-20 is primarily to improve fuel economy by reducing pumping energy and friction - especially while the engine is cold. With a possible trade-off being lower film strength and less protection between parts when hot, and consequently less durability of these parts later. That of course depends on the tolerances between these parts not being any different than in previous engines.

All of that said, without input from a GM engineer who knows for sure, we're all just surmising. All I can say is that if were my rig, I'd feel a little better with 5w-30 in there because I no longer trust the trade-offs that manufacturers are being forced to make due to changing regulations. The goal of the regulations is to increase fuel economy, not durability.

I've done extensive internal engine work on my 6.2, and all of the engine builders and cam experts I spoke with (4 of them) said that they prefer a heavier weight oil in a high performance engine, so I run 5w-40 Euro oil in mine now because I tow a lot, and the valvetrain runs quieter than with 5w-30. I also owned a BMW 328d (diesel) I bought new in 2014, and BMW specified 5w-30 LL04 spec oil for that. LL04 oil comes in both 5w-30 and 5w-40, so lots of guys ran the 40 in their d in summer.

The people at Noria, the oil analysis company would agree with you. Lower viscosity oils are used to help meet Federal fuel economy requirements. Look at all the other ridiculous things they are doing to meet these requirements, such as shutting off the engine when you stop. Since zinc has been removed from oils, you can expect your cams to wear out sooner, too.

Now we have 'better' engines, 'better' lubricants, unleaded fuels, etc., so ask yourself why the engine warranty on a new GM V-8 is only 60,000 miles when warranties were routinely 100,000 miles 50 years ago.

 

[Stbentoak]

Here’s a copy of a GM warranty from 1970. 12 months /12k miles BTB,5/50 powertrain. Still think warranties were better 50 years ago?

 

[CTown Duramax]

I agree with Stbentoak. I am old enough to remember how cars used to be and they mostly sucked. Forget the warranty question, they were dangerous squeaky rust buckets billowing blue smoke after 50k miles - well, almost.

 

[Z15]

Keep in mind that the viscosity recommendations have to comport the CAFE standards under which the viscosity and formulation was tested. That is, if they get even a .1% fuel mileage increase with the new viscosity, the OEM cannot recommend a heavier viscosity.

If the OEM changes their recommendation from the oil formulation used for the official testing, they are subject to fines. That's why the viscosity statements in the manuals state to "go back" to the original formulation recommendations at first opportunity.

One may ask if I can use a 5W-30 temporarily, why can't I use it all the time? One reason--government regulations. The OEM cannot state otherwise, even though there is absolutely no risk with either viscosity. It also gives the OEM an "out" for warranty claims if the recommended oil viscosity was not used.

 

[dbphillips]

I wish there was a 5w-30 Dexos D, so I could just run it and see if my Tahoe stops using a quart between (short) oil changes.

 

[B-train]

0W-20 engine oil can reduce the startup load by making it easier to turn over a cold engine and the impact is felt at higher temperatures than most consumers would think, not simply to what feels cold to humans - warm summers days are cold to an parked engine. Also these newer engines with Variable Valve Timing and Active Fuel Management operate at peak efficiency with the oem recommended viscosity.


Question: Can another oil such as 5W30 that is cheaper and more widely available be used in place of 0W20 oil?

Answer: No. The 5.3L and 6.2L V8 EcoTec3 engines available in the 2014+ Silverado 1500 and Sierra 1500 pickup trucks were designed, engineered and validated to run using 0W20 oil. This is the ONLY oil approved for these engines.

I will politely disagree here. While I understand the viscosity is a game played to eek 1/10ths of gallons of mpg for CAFE, it doesn't mean it's the best choice. I do understand that in AFM engines it may be preferable over a thicker oil.

However, the LT6.6 gas motor recommends 5w-30 from the factory. VERY similar engine architecture (minus AFM/DFM). Why does it run 5w-30? Because the trucks it goes in are not subject to CAFE, plus they know these engines will get used hard in their life cycle. Hence an oil weight that is more robust for the engine load, yet thin enough to work with the newer engines with tighter tolerances.

I've been running 5w-30 in a LT6.2 for over 100k now. Never uses a drop, no weird noises, engine purrs like a kitten. Bottom line IMO is to use an oil that provides the protection needed without succumbing to the BS EPA standards that prescribed the use of the bare essentials to scrape by and check a box.

 

[kerlyb]

Anybody using any other oil than the 0-20w it calls for? Just curious if it would hurt to use a say 5-30w? Thx

 

[Marky Dissod]

However, the L8T 6.6L gas motor recommends 5W-30 from the factory. VERY similar engine architecture, minus Cylinder Confusion.
Why does it run 5W-30? Because the trucks it goes in are not subject to CAFE, plus they know these engines will get used hard in their life cycle.
Hence an oil weight that is more robust for the engine load, yet thin enough to work with the newer engines with tighter tolerances.

Is it possible to be more specific about which motor oils GM recommends for the 6.6L L8T, besides just '5W30 synthetic'?
Are there any unique standards called out, above & beyond '5W30 synthetic'?

 

[dbphillips]

Using GM guidance is kind of suspect, given their lawyers made them say one quart in 2000 miles is normal. It just isn't. And if you have a good engine, it's disingenuous of you to say it is. What they mean is "it will get through the warranty period".

Also, what if you have an .017 LM2? That's right near the middle of the 5w-30 range... Not only that, if you live in a hot climate, you should definitely have something with better high temperature protection. It's EPA nonsense.

 

[Marky Dissod]

Using GM guidance is kind of suspect, given their lawyers made them say one quart in 2000 miles is normal.
It just isn't. And if you have a good engine, it's disingenuous of you to say it is.
What they mean is "it will get through the warranty period".

ENTIRELY agree with this statement.
GM's standards are engineered to the bare minimum necessary to cover GM's arse.
Too many owners keep saying things like 'just go with GM's recommendations', and stop there.

I was NOT suggesting that.
I want to know GM's standards criteria, so I could learn enough about them, to see if it's possible to exceed them.
Some 5W30s are better than others.