# Oil... how does it work? \[split\]

**URL:** <https://forums.speedlife.net/t/oil-how-does-it-work-split/262189>\
**Category:** Shift518 Off Topic\
**Created:** [January 6, 2012, 11:40pm UTC](https://forums.speedlife.net/t/oil-how-does-it-work-split/262189 "2012-01-06T23:40:40Z")\
**Posts on this page:** 1\
**Showing post:** 44

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**Author:** ![Vovchandr](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/vovchandr/32/6275_2.png) [@Vovchandr](https://forums.speedlife.net/u/Vovchandr)\
**Post date:** [January 8, 2012, 11:01am UTC](https://forums.speedlife.net/t/oil-how-does-it-work-split/262189/44 "2012-01-08T11:01:42Z")

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> [@FS: Engine stand](https://forums.speedlife.net/t/fs-engine-stand/47720/2):
>
> low number is indeed thin, and high number is indeed thick.
> 
> What you’re not grasping is that a 5W is PHYSICALLY THICKER in cold temps vs. an SAE 30 in high temps.
> 
> (not sure if this next statement will help or hurt)-a 5W30 at cold temps is THINNER than a straight SAE 30 in cold temps, and the same thickness at high temps.

I’ve edited my post above, not sure if you caught that.

I know that straight oil such as just “30” will be the same at high temp at 5w30, as a straight oil has only been tested at operating temp. That won’t be confusing anybody.

> [@FS: Engine stand](https://forums.speedlife.net/t/fs-engine-stand/47720/2):
>
> low number is indeed thin, and high number is indeed thick.
> 
> What you’re not grasping is that a 5W is PHYSICALLY THICKER in cold temps vs. an SAE 30 in high temps.

Is there a different between SAE thickness rating and being “physically thicker”?

Because then I’m still just as confused. If low number is indeed thin and high number is indeed thick, and one oil rated 0w30 (for example) is going to be thin like 0 at 32deg and thick like 30 at operating temp, that would imply that it gets thicker as it gets warmer.

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