67-81 GM viscosity chart

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I found this in a book for engines covered from 1967 through 1981 and i thought it was interesting that 5w20 was covered in it.
 
SAE 30 above 5 celsius good to know, you can use SAE 30 for most of the year.

5W20 is odd but I think SAE 10 is even more strange. You could run straight grades year round if you wanted to throughout the 70s apparently.
 
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Originally Posted By: carviewsonic
When was the book published?

The copyright says 1981 it sure does provide some good reading this book covers camaro's but my friend said a lot of the info applies to my nova as well.
Here is the oil change recommendation as well.
 
Originally Posted By: maxdustington
SAE 30 above 5 celsius good to know, you can use SAE 30 for most of the year.

5W20 is odd but I think SAE 10 is even more strange. You could run straight grades year round if you wanted to throughout the 70s apparently.


It is 10w not sae 10. Two different things. Don’t ask me what it is but I just know it’s different.
 
I hadn't heard of 5w-20 back then, maybe in the late nineties(?). Then again, I had only been driving for a year or so in 1981.
 
Originally Posted By: jhellwig
It is 10w not sae 10. Two different things. Don’t ask me what it is but I just know it’s different.

The plot thickens!

7500 miles or a year is a long OCI for 1981, 3K OCIs are complete marketing. The truth comes out!
 
I think it's odd that they have 10w30 going past 100 degrees F but 5w30 only goes to 60 degrees? The first number is for cold engine. At operating temps, both oils are 30 weights.
 
Originally Posted By: carviewsonic
I hadn't heard of 5w-20 back then, maybe in the late nineties(?). Then again, I had only been driving for a year or so in 1981.


I started using M1 5-20 in 1978 in a Dodge Slant 6. Kept my engine very clean.
 
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My 1977 Briggs & Stratton generator engine manual mentioned 5w20 as well as thinning another grade with kerosene.

My dad's 1980 ford fairmont had similar 7500 mile/ 1 year drains. They compared the low maintenance of it to the 1970 Maverick in marketing materials. 1970 took plugs every 12k due to leaded gas and points ignition and more frequent OCIs too.
 
20w-20 was commonly used. I used it and got it at Sears in their garage bringing my own container from their bulk tanks. I drove my 65 Rambler Classic three speed with overdrive cross country using it. The Rambler didn't use any oil at all driving from Il to CA in 100 degree heat using 20w-20. I kept the engine tuned to spec and at idle inside the car it was not detectable the engine was on. People would say, your engine is off.
 
Originally Posted By: Dave1027
I think it's odd that they have 10w30 going past 100 degrees F but 5w30 only goes to 60 degrees? The first number is for cold engine. At operating temps, both oils are 30 weights.

Don't forget oils in the 80's weren't what they are now, 5W30 weren't as robust and shear resistant as they are.
 
Originally Posted By: Popsy
Originally Posted By: Dave1027
I think it's odd that they have 10w30 going past 100 degrees F but 5w30 only goes to 60 degrees? The first number is for cold engine. At operating temps, both oils are 30 weights.

Don't forget oils in the 80's weren't what they are now, 5W30 weren't as robust and shear resistant as they are.


Yup I mostly used 10w40 back then.
 
Originally Posted By: Popsy

Don't forget oils in the 80's weren't what they are now, 5W30 weren't as robust and shear resistant as they are.


AGREED.

5W-30's of those days did NOT hold up as well as the 5W-30's of "now-a-days" do!!
 
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