How detrimental is it to...

Red__Zed · 01-12-2011, 07:39 PM

Quote:

Originally Posted by ChrisSlicks

Because it isn't an SAE-5 oil, it is an oil blend. A 5W30 isn't going to perform the same as a SAE-5 or an SAE-30, most of the time it is somewhere in between. It's properties are such that it can pass the minimum test for SAE-30, however there actually isn't any standardized test for Winter weight and most oils certainly wouldn't pass the test of SAE-5.

The viscosity numbers quoted (60 cSt @ 100F) is an average from actual manufacturer test data. On a cold start on a cold day it will be slightly higher, probably around 80-90.

Maybe I'm confused. I was under the impression that an SAE 5W-30 met the 5W low temp test, as well as the 30 weight 100C test, and behaved as in the following chart:

I know there's a lot of misinformation out there though, and I probably got some of it-- I won't pretend to know everything about oil. I am genuinely curious about how they rate the winter oils, if there is no standardized test. I was under the impression that the timed orifice method was used for the 100C test, and then it had to meet a standard at 40C, based on the cranking/pumping characteristics.

ChrisSlicks · 01-12-2011, 08:34 PM

Quote:

Originally Posted by Red__Zed

Maybe I'm confused. I was under the impression that an SAE 5W-30 met the 5W low temp test, as well as the 30 weight 100C test, and behaved as in the following chart:

I know there's a lot of misinformation out there though, and I probably got some of it-- I won't pretend to know everything about oil. I am genuinely curious about how they rate the winter oils, if there is no standardized test. I was under the impression that the timed orifice method was used for the 100C test, and then it had to meet a standard at 40C, based on the cranking/pumping characteristics.

In a perfect world they would want the oil to have the ideal properties of both, both the reality is that it is currently impossible. Trade offs have to be made at either end. Given that the oil spends most of its live at operating temperature they make a few more trade offs in the lower range.

Red__Zed · 01-12-2011, 08:41 PM

Quote:

Originally Posted by ChrisSlicks

In a perfect world they would want the oil to have the ideal properties of both, both the reality is that it is currently impossible. Trade offs have to be made at either end. Given that the oil spends most of its live at operating temperature they make a few more trade offs in the lower range.

I understand that, but I thought it had to meet the cranking and pumping specs of the lighter weight oil at 40C?

ChrisSlicks · 01-13-2011, 06:49 AM

Quote:

Originally Posted by Red__Zed

I understand that, but I thought it had to meet the cranking and pumping specs of the lighter weight oil at 40C?

They do. But it doesn't have to pass the full SAE test regiment that they do at operating temperature. The cranking and pumping tests aren't very tough, basically just there to assure that your oil won't turn to molasses at lower temperatures. It's the other standard tests such as the API (currently SN standard) that are more important and test the wear resistance and longevity of the oil.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Added weight detrimental?	ddvette9	Nissan 370Z General Discussions	14	02-28-2010 11:37 AM