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

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


so long



I'm not sure whether you're bashing SAE and DIN or amateur tests.


Industry standards, more often than not, document a performance or condition that is attainable by that industry. Oil is and has been an example of that.

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Lesson of the day? Run the 0w20.

Dexos is not a GM oil is is a standard they have set for oils to meet to be considered for use in GM vehicles and for licensing purposes. Your 5w-30 oil you want to use meets the Dexos standard, so

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 ta

...amateur-test, specs, asphalt-dyno, butt-meter.

Call it whatever you want. :)


My point is that all of the "test"( :rolleyes:) oils where branded with the same numbers.


This is suggesting to Otto Normalverbraucher (or John Doe) that the 4 samples should at least behave close to each other. Like the Amsoil and Mobile1.


so long


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  • 6 years later...

Intetresting, appears typical "recorded info".

After over 50 years experience the same question is unanswered.

Political and environmental concerns out weigh reliability and long engine life. Auto maker will be happy if vehicles are crushed prior to 250,000 km. Engines in my part of the world experience harsh conditions, -40 to + 40 C so my info is based on this.

Engines subject to severe use, have, and still are recommended to up the viscosity, even the newer high tech versions. Auto makers in efforts to comply with government emissions and other requirements quite simply just "water down" the oil viscosity. Also high stress engine in marine applications were recommended straight SAE 30, and 20 50. 

As for mileage, the old 5.3 engines of say, 1999 got as good mileage as the new engines and were emissions compliant. A lot of engineering, and over engineering has not made significant improvements. Reliability and long life are compromised, in fact, unfortunately no longer a consumer concern, Fact!


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Crap can be an inch thick or five miles thick. You still won't  know where the floor is. And that is just where everybody likes it to be. A thread well meant could be 90% true or 99% crap and 99 out of a 100 will not be able to tell the difference. You can never uncover the truth as long as one person is shoveling crap on it. Boy do OEM's and Oil producers love their shovels. Forum people love to eat and repeat...


I worked my entire life in this business and what was known and what was marketed came from different planets.


How do you control the public and publics perceptions? Lie from the heart and deny access to the truth. I works in government, in religion and even in oil-tire-sparkplug wire-blah blah blah...whatever you would like to argue in ignorance over.


It is so bad you can literally tell the truth and no one will believe you. :rolleyes:


There is always one person who drove home drunk for years, never getting a DUI or hurting anyone that will tell you, and convince many that driving drunk is as safe as anything you can do. 😡   

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