5W-20 vs. 5W-30 vs 10W-30

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quote:

Originally posted by Buford T. Justice:
My car, a 1998 Ford Mustang GT, has the 4.6L engine that is qualified to run 5W-20 according to Ford. But would I want to?

You should try it. It really woke up the 4.6L in my 1996 GT. Previous owners used 30 weight dino in my engine, so rings were coked up and I think ring/bore wear was much higher than necessary (1qt/500mi consumption at first).

My best oil so far (among many tried) is Motorcraft 5W-20 spiked with Delo 400 SAE30 (1qt/2500mi consumption). Next best is Pennzoil Platinum 5W-20/5W-30 mix, but the oil consumption is higher (1qt/1000mi). WOT is the norm, so judge the oil consumption on that basis.
 
5W, 10W, 15W, 20W

Has NOTHING to do with weight.

Has only to do with its ability to flow at lower and lower temperatures only.

The W does not stand for weight.
 
Bryanccfshr: Good info.

Triple_Se7en: Good point, but it might be clsoe. I have never seen 5W-40 poured, etc.

Rodbuckler: I am tempted to try it, but it sounds to me like it will burn oil. I guess our engines are too accustomed to 5W-30.

BlazerLT: Yes I know the W stands for weight, but it is still 5W weight meaning 5 winter weight right?
 
No, it's not 5 winter weight. Also, your engine doesn't get "used to" an oil. Animals get used to their surroundings, but, It's a machine. The oil either lubricates it sufficiently, or it doesn't. It either burns off, or it doesn't. The thinner the oil, the faster it flows at any given pressure, and flow is one of THE most important parts of lubrication design. If your engine is designed to run on 5-20, run it.
 
quote:

Originally posted by Buford T. Justice:
Rodbuckler: I am tempted to try it, but it sounds to me like it will burn oil. I guess our engines are too accustomed to 5W-30.

My engine definitely runs better on the 20 weight oil. It's just that the full synthetic 20 weight tends to sneak out under full throttle operation. The blends have worked well.
 
Changing an oil weight will not hurt anything. Titan is right! An oil either lubricates sufficiently or it doesn't. The factor difference theory is just plain wrong! Buford you need to go back and re-read this thread and the info links.
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What are you talking about? It makes perfect sense if the number before the W is the same. 5W-40 is thicker than 5W-20 and 5W-30. 5W-30 is thicker than 5W-20 but thinner than 5W-40.

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quote:

Originally posted by Blue99:
Buford, I think the answers to these questions will become self evident if you become acquainted with the SAE J300 Viscsoity Chart.

5W is a minimum 3.8 cSt @ 100C

10W is a minimum 4.1 cSt @ 100C

A SAE 30 viscosity grade oil is 9.3 to 12.5 cSt @ 100C.

quote:

both 5W-30 and 10W-30 have thinned into 30 weight oil which is lighter than 5W and 10W oil.

Based on the SAE J300 chart, this statement is off the mark.

Buford, refer to the J300 chart in the link I provided.

To keep it simple, the xW rating comes from column 2.

The SAE viscosity grades are defined in columns 4 & 5 for the 20, 30, 40, 50, 60 viscosity grades.

Example: SAE 40 is 12.5 cSt minimum to less than 16.3 cSt maximum.

A 5W-40 meets 6600 max cP @ -30C,(cold) and is between 12.5 cSt and 16.3 cSt @ 100C (hot).

That's it in a nutshell!
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quote:

Originally posted by Buford T. Justice:
What are you talking about? It makes perfect sense if the number before the W is the same. 5W-40 is thicker than 5W-20 and 5W-30. 5W-30 is thicker than 5W-20 but thinner than 5W-40.

Depending on the temperature, a 5w20 could be thicker than a 5w40. It's all relative. All things being equal, a 5w20 will always be somewhat thinner than a 5w40. But depending on the base oils used, you could have a 5w40 that is thinner at sub zero temps than a 5w20.
 
The numbers on the bottle matter. It provides a relative quantification of the properties of that particular oil. It is true that 5w-40 is thicker than 5w-20 and 5w-30. Also it is true that 5w-30 is thicker than 5w-20 and thinner than 5w-40. However, the factor difference theory (4,6,8)is just incorrect.
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quote:

Originally posted by Buford T. Justice:
BlazerLT: Yes I know the W stands for weight, but it is still 5W weight meaning 5 winter weight right?

No, it is just a scale of how the oil can handle lower temperatures.
 
At any rate, I doubt there would be any harm using 5W-20 instead of 5W-30 especially if your owner's manual specifies 5W-20. I need to read some UOAs on 5W-20. I will probably wind up sticking with 5W-30.

That is another thing that kind of bugs me actually. 5W-30 will shear down to pretty close to what 5W-20 is new. I suppose water can cool things down quicker than thick syrup, lol.

Is there really much difference between 5W-20 and 5W-30?
 
quote:

Originally posted by Buford T. Justice:

quote:

Originally posted by TomJones76:
Wrong.
5W20s have a slightly lower viscosity at room temp than 5W30s have, and usually a slightly lower minimum pumpting temp.


That is true, but they both weight the same at 0° C right?


Others have answered better than I can, but to respond to you, the scale isn't "balanced" on the bottom at 0 celsius.
At the top end the scale "balances" at 100C or 210F.
At the bottom, it doesn't "balance" except if you're comparing oils of the exact same cold-temp rating, and even then the "balance" can be imprecise.
 
"Really much difference?"
Not a ton, especially between thin 30 and thick 20.
The fuel economy difference is expected to be something like 0.3%....
 
quote:

Originally posted by Buford T. Justice:
Is there really much difference between 5W-20 and 5W-30?

Yes. Try the 5W-20 in your 4.6L Modular Motor and you will be hooked. You will never go back to that 30 weight concrete. If it uses oil you can always thicken and sticky it up some with the Delo.
 
OK, so here is what I have learned from this thread so far...

There is no winter weight.

5 is what the oil weighs at cold crank then it thins into a 20 or 30 weight as it is heated.

The heated oil is thinner than what it is cold.
 
quote:

Originally posted by Titan:
No, it's not 5 winter weight. Also, your engine doesn't get "used to" an oil. Animals get used to their surroundings, but, It's a machine. The oil either lubricates it sufficiently, or it doesn't. It either burns off, or it doesn't. The thinner the oil, the faster it flows at any given pressure, and flow is one of THE most important parts of lubrication design. If your engine is designed to run on 5-20, run it.

Now wait a minute. Changing oil weight won't hurt anything? I have always heard from very good mechanical sources that this is bad.
 
OK, I think I am starting to understand something maybe. 5W just means the oil can be pumped at a certain temperature which is lower than what a 10W can be pumped at. 0W can be pumped at an even lower temperature.

Also, with the same W number (in this case 5W), the factor difference determines how thick the oil is. 5W-20 is very fluid as compared to 5W-40 since 5W-20 has a factor difference of 4 whereas 5W-40 has a factor difference of 8. 5W-30 has a factor difference of 6.
 
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