Oil Viscosity.....GM and my local Service Manager

GsBowtie · July 14, 2015

Well.... At 100C the viscosity of the 5W-30 is 26% higher than the viscosity of 0W-20 for the same Mobil1 product line. Is 26% huge or not? I think it's certainly enough of a difference to have an effect on pumping and windage losses, but since we have no idea how large those are in the overall scheme of things, it may or may not be visible in actual use.

As long as GM is okay with the film strength in the thinner product, I'll prolly stick with their recommendations. On the other hand, If I were pulling a heavy trailer cross-country in mid-July, I might get wild and crazy with something a bit thicker at the higher oil temperatures you'd expect to encounter.

Agreed. The engineering in these engines today is very extensive. Again, I appreciate all of the information and contributions to this thread

Spurshot · July 14, 2015

Here's an interesting related blog on oil wear protection test data at 100C. Mobil 1 5w-30 is very highly ranked.

https://540ratblog.wordpress.com/2013/06/20/motor-oil-wear-test-ranking/

Edited July 14, 2015 by spurshot

chuckl1218 · July 14, 2015

Well I just got an oil change on my '14 silverado with the 5.3l engine at the dealership and guess what.....they used 5W-30......

The window sticker my dealer put on the windshield on mine said 5W-30, but service manager assured me they used 0W-20.

Sent from my iPhone using Tapatalk

FL335i · July 14, 2015

The joe dirt comment was meant to be funny man. Relex. This is a forum. If I have to be PC, ruins the fun. GM has stated in numerous locations what visc to use. They've put it on the oil cap it self, owner's manual and a few online tech articles published by GM describing the new oil pump design. Engines have gotten tighter, hence the thinner oils. They've designed the shear of the oil film on the bearings. They got all that figured out. I love 0-20. Some engines/machinery run on compressed air for bearings.

Edited July 14, 2015 by FL335i

redwngr · July 15, 2015

To answer this specifically, yes.

Part of what bugs me about the first post is it's verbatim GM nomenclature. Of course they want you to buy their Dexos oil so they are going to tell you to run it.

The part I found interesting was the question as to whether running a different viscosity would cause engine damage and they were non-committal on that aspect. I believe that is because it won't, but of course I have no proof of that.

Based on the information however, I will Run 0-20W at least until my powertrain warranty is out. I do have an email from my service manager confirming I can upgrade to a full synthetic oil at least so my plan is to do that and run Full Synthetic.

Dexos is NOT 'their oil'.

Dexos is an oil specification.

Valvoline has several oils that meet the Dexos specification, including a full synthetic 0w-20, a 5w30, a 5w30, etc....

If you want to use the Valvoline full synthetic, why not use the 0w-20 that is listed as meeting the Dexos spec?

Here is the current list of oils meeting the Dexos spec -- several viscosities are included.

http://www.centerforqa.com/gm/dexos1-brands

FWIW, to get the designed oil flow thru a journal bearing, requires the correct oil pressure and oil viscosity.

Edited July 15, 2015 by redwngr

GsBowtie · July 15, 2015

Dexos is NOT 'their oil'.

Dexos is an oil specification.

Valvoline has several oils that meet the Dexos specification, including a full synthetic 0w-20, a 5w30, a 5w30, etc....

If you want to use the Valvoline full synthetic, why not use the 0w-20 that is listed as meeting the Dexos spec?

Here is the current list of oils meeting the Dexos spec -- several viscosities are included.

http://www.centerforqa.com/gm/dexos1-brands

FWIW, to get the designed oil flow thru a journal bearing, requires the correct oil pressure and oil viscosity.

Excellent info and list. Thanks for the help. I think I'll run valvoline full syn 0-20w and a wixXP oil filter at the first oil change at 5k. Or i may let the dealer do it [probably not! Lol ]

Thanks again

G

GsBowtie · July 15, 2015

The joe dirt comment was meant to be funny man. Relex. This is a forum. If I have to be PC, ruins the fun. GM has stated in numerous locations what visc to use. They've put it on the oil cap it self, owner's manual and a few online tech articles published by GM describing the new oil pump design. Engines have gotten tighter, hence the thinner oils. They've designed the shear of the oil film on the bearings. They got all that figured out. I love 0-20. Some engines/machinery run on compressed air for bearings.

10-4 we're good. Thanks

ghgmi · July 15, 2015

And you prove my point exactly. I think, I'm not sure though. This conversation has gone way over my head now. The Engineering department at my school must have been lacking the class where they taught the merits of hyperbole in place of data or theory in technical arguements. I guess I'm just not qualified to understand what you're trying to say and how you are backing it up. I know how to read data and equations, but snide comments confound me. Second order snide comments are even worse! Maybe if I can find a text book for Differential Hyperboles I can brush up.

Sheldon?

Spurshot · July 16, 2015

I stumbled on a YouTube wher a couple guys cooled 4 oils down to -40F and did a simple pour test. The oils were Amsoil, Mobil 1, Royal Purple, and Walmart Dino. All were the same weight. The fastest pour by far was M1, followed by Amsoil, and way back, RP. The Walmart Dino was like taffy.

GsBowtie · July 16, 2015

Wow that is interesting for sure. I'm suprised about the RP. I hear good things about it but never tried it

spectaculous · July 17, 2015

Here's an interesting related blog on oil wear protection test data at 100C. Mobil 1 5w-30 is very highly ranked.

https://540ratblog.wordpress.com/2013/06/20/motor-oil-wear-test-ranking/

If that site is legit, then Mobil1 Advanced Fuel Economy 0W-20 was the highest ranked 0W-20. And since the owner's manual states that "SAE 0W-20 is the best viscosity grade for the 5.3L and 6.2L V8 engines", that would make it the best GM-approved oil for those engines, at least wear protection-wise.

Good to know that what I've been doing is right!

Spurshot · July 17, 2015

If that site is legit, then Mobil1 Advanced Fuel Economy 0W-20 was the highest ranked 0W-20. And since the owner's manual states that "SAE 0W-20 is the best viscosity grade for the 5.3L and 6.2L V8 engines", that would make it the best GM-approved oil for those engines, at least wear protection-wise.

Good to know that what I've been doing is right!

I'm on my third truck that I ran M1 in from the first change to the last. I'm at about 390,000 total miles over those three trucks. No problems yet. I also ran either K&N or M1 filters, mostly the latter.

FL335i · July 18, 2015

I think as long as you run any dexos 1 approved 0-20 syn, and a quality filter (ie- AC, Wix, M1 Etc) the engine oil will be the last failure item on the list IF you keep the truck that long to find out. Say you change the oil every 7,500mi per the OLM. You keep the truck 10yrs and drive like me 25k-30k/yr. So the truck will have 250k-300k in 10yrs. You'll have done 33-40 oil changes. Say the difference between running M1 vs Synpower is $10 per oil change. It's every bit of that IIRC from two weeks ago. The 5qt jugs are like $5 more for M1 @ walmart, then you gotta buy the 3 quarts which are like 2-3 more ea. So at 300k miles and 10yr later is your truck worth $400 more b/c you ran M1 over synpower? Is the engine going to be in any better shape? Even if it is, the truck is by far shot. And can you imagine the new silverado they'll have out in 2024? Need to keep things in check. And we know based on UOA's that M1 and Synpower are both top tier oils and it's a personal preference at that point. And I think Pennzoil started carrying the dexos1 on some of their oils recently too. Just run a quality dexos 1 0-20 full syn, change it per the OLM, run a quality filter and find something else in life to spend your time on.

Spurshot · July 19, 2015

https://youtu.be/uQ_vxdO_9nc

This was an enlightening video on extreme cold oil flow. I would have expected better performance from Amsoil and RP. I don't live where it gets this cold and it's rare that I would see this temp with my truck. But some of you do. I'd be buying a oil pan heater, in addition to a block heater, regardless of which oil I ran.

Edited July 19, 2015 by spurshot

j-ten-ner · July 19, 2015

This was an enlightening video on extreme cold oil flow. I would have expected better performance from Amsoil and RP. I don't live where it gets this cold and it's rare that I would see this temp with my truck. But some of you do. I'd be buying a oil pan heater, in addition to a block heater, regardless of which oil I ran.

That makes me really wonder why in hell anybody even bothers to invent SAE and DIN or any other norms and standarts.

so long

j-ten-ner