I was always under the impression that the first number in oil viscosity was for winter pumpability. This means that a 5w-30, is a 5 weight oil below zero degrees as far as pumpability, but a 30 viscosity oil at running temp.

If this is true, isn't 0w-30 a straight 30 weight oil? Obviously, there is no point in putting a zero weight oil in your engine, right.


I guess the misconception on my part is surrounding the "w" figure...some people think that if you put a 0w-30 weight oil that it will flow better in cold weather than a 5w-30 oil. Is 0w-30 a straight 30 weight oil. If it is, why are people putting it in their engines in near freezing weather?

thanks for the clarification

 

I don't have the answer to all your questions, but I do know that 0w-30 is NOT the same as straight 30 weight. 30 weight does not have the cold flow characteristics that 0w-30 does. 0w-30 which is only available in a syn. is extremely thin. I don't think there is any engine made that requires this. Straight 30 is recommended in freshly rebuilt engines because it does not have the detergent additive.
No, 0w-30 is not the same as straight 30. They are actually on opposite ends of the spectrum.

 

Thanks for the information Silv/Blu.

That was a question that was bothering me for a while.

 

In answer to your queston, the way I understand it the 0w is the pourability of the oil at that temp. and the 30 is the weight at operating temp. To get all the info you ever want to know about oil and probably more than you want to know go to www.bobistheoilguy.com

 

One hell of a nice site.
I found a lot of info there on the 5w-20 oils...

I've been running Redline 5W-30 for 15,000 mi. at 5,000 mi intervs. When I go to the track to run the 1/4 mi, should I use a 40 weight oil?

 

If you are running your street vehicle at the drag strip I would leave the Redline in it.

 

The first number is the wieght of the oil as measured though a viscometer at 40C. Basically room temperature.

A certain visosity in centistokes cSt is what classifies the API Viscosity.

The second number is the viscosity as measured at 100C.

I have a viscosity chart but not with me. It comes on the back of all of my oil analysis results.

Anyhow to get a multivis oil you take a base oil say 5wt and add VII's viscosity index improvers. When the oil is heated these polymers unwind to make the oil seem thicker(actually not as thin) Becuase all oil thins when it is heated.

So if yo think of it this way a 5 w30 is a 5 weight oil at 40C, but when it is heated only thins to what a straight weight 30 would be at 100C(212degrees)

The "W" stands for Winter, which indicates that the oil is suitable for winter use.

With the Advent of Viscosity Index Improvers straight monograde oils have virtually become obsolete.

Also in the last 10-15 years improvements in VII's have allowed higher Viscosity Indexes and wider viscosity ranges. Also Better VII's hold up over longer drain intervals

Which brings up a point that it is wise to use a high quality oil, as some of the cheaper VII's can break down in as little as a 1000 miles.

 

The answer is NO, unless you want to lose HP!!

Now if you were racing over a period of hours where the oil temp would be significantly over 212 degrees for a long time, you would want to run a higher weight oil.

But since you are only running the oil hard for what 20 seconds, I don't see much heat being produced.

Stay with the Reline 5w30 for all conditions.

 

Thanls Msparks,

That was an easy to understand explanation. The guys at www.bobistheoilguy.com are informative but get real technical and lose me.

 

Right on !