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

GsBowtie · July 12, 2015

Run 0w-20 and be done with it. Too many of you guys out there still want to run 20w-50 in their engines because they believe they need "thick" oil for protection

Yes that's what i am going to do.

Thanks for your reply

FL335i · July 12, 2015

I read the owner's manual on my '14 and the way they wrote it, regarding oil visc, they recommened 0-20. They specifically DO NOT allow 10-30 + . So left the 5-30 in the gray. IMO, they did this b/c if a dealer happens to dump 5-30 in a newer truck, it won't "void the warranty" and the dealer/GM can show them the book which states it it's not addressed. Just my 2 cents. I run full Syn Dexos approved 0-20. Oil and engines have progressed dude. the new 5.3L has a very advanced oil pump and i WOULD ONLY RUN 0-20!!!!! I've owned hondas, Fords etc. 0-20 is not new. Honda and Ford have been running it for 15yrs man. Get over the 4 barrel camaro joe dirt 20w-50 oil mentaility and run what GM specs and move on in life.

j-ten-ner · July 12, 2015

...the 4 barrel camaro joe dirt 20w-50 oil mentaility...

loool

you made my day

so long

j-ten-ner

Lawnmower2020 · July 12, 2015

It's true that GM specifies 5W30 for the 6.2L Corvette variants of the Gen-V engines.

According to Mobil's product data sheets there's quite a bit (a lot more than I expected to see) difference in viscosity between 0W-20 M1 Dexos and 5W-30 M1 Dexos:

Viscosity at 100C...... 0W-20 = 8.7 5W-30 = 11.0 cSt

Viscosity at 40C...... 0W-20 = 44.8 5W-30 = 61.7 cSt

Obviously, there's a lot of overlap in viscosity over normal engine operating temperatures, but there's no getting around the fact that temperature for temperature, the 0W-20 is a lot thinner.

I just had my truck's 5.3L engine oil changed at the dealer last week. Asked for Mobil1. Guess what they put in: 5W-30.

On edit: corrected the temperatures (100C and 40C)

Edited July 14, 2015 by Lawnmower2020

FL335i · July 13, 2015

^Bingo. Hence why only I work on my car.

Jon A · July 13, 2015

It gets worse than that when you look at the HTHS @ 150 measurements which is what you should be looking at if the concern is engine wear while towing in the summer. For my favored Redline oil:

0W20 2.9

5W30 3.7

0W40 4.0

15W50 5.8

Mobile 1

0W20 2.7

5W30 3.1

15W50 4.5

Here are a couple interesting notes on the subject from Redline: http://www.redlineoil.com/news_article.aspx?id=291

robvas · July 13, 2015

Run 0w-20 and be done with it. Too many of you guys out there still want to run 20w-50 in their engines because they believe they need "thick" oil for protection

Reminds me of my dad. Refuses to even put 5W-20 in his F150 when the oil cap says so. "I like the protection of 10W30", and then runs 20W50 in the summer.

TxTruckMan · July 13, 2015

GM doesn't know what they're talking about - run 70W90 instead. It's thicker, and therefore better.

Jon A · July 13, 2015

GM does know what they're talking about. http://www.chevrolet.com/content/dam/Chevrolet/northamerica/usa/nscwebsite/en/Home/Ownership/Manuals_and_Videos/02_pdf/Corvette_TrackPREP_v23.pdf

It's interesting how closed minded so many people are on this subject. Provide evidence from credible sources and they'll pretend it doesn't exist and keep repeating the same thing over and over.

TxTruckMan · July 13, 2015

I also change my oil every 2000 miles because the OLM is designed by GM to make my engine explode at exactly 100,001 miles.

Edited July 13, 2015 by Black03Yukon

Jon A · July 14, 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.

GsBowtie · July 14, 2015

Get over the 4 barrel camaro joe dirt 20w-50 oil mentaility and run what GM specs and move on in life.

I'm good with all the comments and discussion in this thread so far except the asinine one i quoted. You don't know me from Adam or what my technical background or experience is. Keep the personal shots out of this thread. If you have something meaningful to contribute please do so. Be respectful.

There's not a huge difference between 0-20w and 5-30w and that's why i was initially thinking about this matter. I'm going to run 0-20w for now due to the info in this thread so thanks for your help.

TxTruckMan · July 14, 2015

Sarcasm - the use of irony to mock or convey contempt

dbt1127 · 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......

Lawnmower2020 · July 14, 2015

There's not a huge difference between 0-20w and 5-30w

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.