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

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quote:

Originally posted by Rodbuckler:

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.


If you start to burn oil after switching from a 30 to a 20, I suppose its reasonable to assume that the oil burning is caused by the thinner oil. But why not just switch back to a 30, rather than using some additive to thicken it? I'm not in favor of thickening by additive as against simply buying a thicker oil
 
I am gonna stick with 5W-30 for the life of my car. It burns no oil, runs smooth, and gets 25 MPG. Not bad for a fast V-8 car at all
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5W-20 probably won't be too great for people seeking long service life like I am. I am hoping to get 500,000 miles out of my car.

I wonder what oil weight(s) Irv Gordon runs in his 2.25 million mile car.
 
quote:

Originally posted by Buford T. Justice:
http://www.mobil.com/USA-English/Lubes/PDS/GLXXENPVLMOMobil_1_5W-20.asp
http://www.mobil.com/USA-English/Lubes/PDS/GLXXENPVLMOMobil1_5W-30.asp

Just looking at the numbers there, the performance appears to be pretty close between 5W-20 and 5W-30. Strangely 5W-30 pours at a lower temperature while being a bit thicker than 5W-20.

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? I don't know. It would seem to me the engine would make more noises and oil would start burning.


I had a 95 Mark VIII with the 4.6L engine. Used 5w30 Motorcraft year round - never consumed any oil. Never added a drop between 5K oil changes. Fairly warm climate (Atlanta, GA) - extremes are around 0 degrees F to 100 degrees F, but normally low 20's in winter to mid 90's in August. Just wish the tranny had been as good as that 4.6L DOHC rocket!
 
Yes the 4.6L Ford engine is a real performer. I may still try 5W-20 as there are a few things about it that make sense at least to me...

1) It is thinner. This means it MIGHT provide better start up protection than 5W-30. Also, thinner liquids can move heat quicker than thicker ones.

2) It is recommended. My 1998 Ford Mustang GT with the 4.6L engine is one of the cars that has been 'revised' to use 5W-20.

3) Better oil. All of the 5W-20 oils are the latest Group III/IV which makes consumers use better oil.

HOWEVER, I might stick with 5W-30...

1) My car has always used it and runs PERFECTLY fine.

2) I don't think there is much difference in weight and fluidity between the 5W-20 and 5W-30.

3) My oil pressure gauge goes straight to the recommended pressure on start up which to me means that the oil is on the critical parts that wear down at start up when no oil is on them. It is instantaneous. There is no delay.

4) Thicker oils quiet engines. Engines will wear down no matter what. The thickest oil you can safely run (comparing 5W-20 to 5W-30) should be used.

5) Oil shears down with longer use. A 5W-20 oil after 5K miles may be more like a 5W-15. A 5W-30 may be more like a 5W-25. Those numbers may not be exact and probably depend on the brand of oil and base stock used. Mobil 1 EP 5W-30 is thicker than Mobil 1 5W-30. I thought I read a UOA that the Mobil EP 5W-30 was actually a mid 30 weight oil.

6) 5W-30 is a thin oil already. I don't think the slightly 'thinner' 5W-20 would be a benefit.

I may try 5W-20, but I am in no gut rush to try it. I am perfectly happy with 5W-30.

I know my situation is different than most people here. Most have a car that came with 5W-20 and want to run 5W-30. I have a car that came with 5W-30 that can use the 5W-20 according to Ford.

The average fuel economy saved is .5% so instead of getting 25 MPG, I would 25.125 MPG. Not a big deal, lol.
 
Forget the gas mileage increase. You won't notice anything significant. I dropped my oil viscosity into the 20's because of unacceptable power loss to the oil system with the 30 weights. You will notice the difference the instant the engine fires with 5W-20 in it.

You can always thicken it up when you top off if the motor feels harsher, or uses oil. My high-mileage 4.6L loves the oil at the high side of the 20 range, and with some smooth conventional oil blended in.
 
quote:

Originally posted by Buford T. Justice:
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.


NO!

the 5 in 5w30 does NOT stand for WEIGHT!
 
quote:

Originally posted by Buford T. Justice:
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.


Yes you did, you said it right there, stop lying.
 
No I didn't. I said the oil weighs 5W when cold. I suppose I should have said 5W is capable of flowing at a cold temperature which is -25 degrees C. Since it can flow at that temperature, it has a viscosity of a 5W weight oil. At 100 degrees C, it has a viscosity of a 30 weight oil.

Maybe these are more clear than I am...

http://auto.howstuffworks.com/question164.htm

"The viscosity grade (for example, 5W-30) tells you the oil's thickness, or viscosity. A thin oil has a lower number and flows more easily, while thick oils have a higher number and are more resistant to flow."

"The first number indicates the viscosity of the oil at a cold temperature, while the second number indicates the viscosity at operating temperature."

http://www.thecarconnection.com/index.asp?article=4833

"The numbers in motor-oil nomenclature refer to the viscosity (thickness) of the oil. A higher number corresponds to thicker oil, while a lower number refers to thinner oil. The numbers themselves are supposed to correspond to a set of real, measurable qualities in the oil, one of which is the viscosity index. In multi-viscosity oils, the left number refers to cold behavior of the particular oil, while the right number refers to its hot (100 degrees Celsius) behavior. So, for instance, 5W-30 oil would flow well when cold like 5-weight oil, but protect at high temperatures like 30-weight oil."

http://www.boss302.com/oil.htm

"The first number IS the weight of the oil at cold start-up, so a lower number means a thinner oil that will be pumped up more readily."

"Now, the first number in a multi-vis oil describes its viscometrics at cold start-up. (engine off for 4 hours or longer, regardless of the outside ambient temperature)."
 
quote:

Originally posted by Buford T. Justice:
No I didn't. I said the oil weighs 5W when cold. I suppose I should have said 5W is capable of flowing at a cold temperature which is -25 degrees C. Since it can flow at that temperature, it has a viscosity of a 5W weight oil. At 100 degrees C, it has a viscosity of a 30 weight oil.

Maybe these are more clear than I am...

http://auto.howstuffworks.com/question164.htm

"The viscosity grade (for example, 5W-30) tells you the oil's thickness, or viscosity. A thin oil has a lower number and flows more easily, while thick oils have a higher number and are more resistant to flow."

"The first number indicates the viscosity of the oil at a cold temperature, while the second number indicates the viscosity at operating temperature."

http://www.thecarconnection.com/index.asp?article=4833

"The numbers in motor-oil nomenclature refer to the viscosity (thickness) of the oil. A higher number corresponds to thicker oil, while a lower number refers to thinner oil. The numbers themselves are supposed to correspond to a set of real, measurable qualities in the oil, one of which is the viscosity index. In multi-viscosity oils, the left number refers to cold behavior of the particular oil, while the right number refers to its hot (100 degrees Celsius) behavior. So, for instance, 5W-30 oil would flow well when cold like 5-weight oil, but protect at high temperatures like 30-weight oil."

http://www.boss302.com/oil.htm

"The first number IS the weight of the oil at cold start-up, so a lower number means a thinner oil that will be pumped up more readily."

"Now, the first number in a multi-vis oil describes its viscometrics at cold start-up. (engine off for 4 hours or longer, regardless of the outside ambient temperature)."


So the oil is thinner when cold then right?
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It would be cool if Ford or another manufacturer recommending 5W-20 for all its engines perhaps had a 30 minute special on TV showing why using 5W-20 is better than 5W-30 which most all of the auto manufacturers use to recommend. GM is still recommending 5W-30. Are they not concerned about CAFE standards and saving vehicle owner's .5% of their gas?

I am profoundly curious as to why Ford, Honda, Toyota, etc. decided to make engine clearances and bearings and such use tighter clearances so they would have to use thinner oils. It doesn't make any sense to me. In fact, I wonder if it is true.

However, quite a few of the 5.7L Hemi owners have to run 5W-20 as the engine shuts down cylinders when the vehicles using that engine are at a constant speed. The thing that makes this 'cylinder killer' operate does indeed have tight clearances.

Then the old argument that to me is still a very valid one is heat. You want the oil to be thick when the weather and engine are both hot. It really isn't an argument. It is a fact. Thick hot oil protects engines better than thin hot oil.

Remember, with 5W-30 or an other multi-weight oils, hot 30 weight is much thinner and more fluid than cold 5 weight in winter.

To be honest and no offense to anyone, I don't think any of us here can really answer the question. None of us are in the know.

But one thing is for certain, it is generally best to follow the recommendations in your vehicle's owner's manual.

My 1998 Ford Mustang GT with the 4.6L V-8 engine is one of the cars Ford says to now use 5W-20 in as opposed to using 5W-30 which the vehicle's owner's manual has always specified and the car has always used. I know the clearances and bearings in my engine are no tighter than when they were all new. I sent an e-mail to Ford which will hopefully be answered asking why should I use 5W-20 instead of 5W-30. If I receive a response, I will happily share it here on BITOG.

This image from a vehicle owner's manual (not sure of the model or make) interests me...

 -


As you can clearly see, both 5W-20 and 5W-30 protect to the same temperature range and cover the same temperature range as 10W-30. All 3 of these weights appear to cover you to 110°F outside temperature. I am skeptical that a 20 weight hot oil can protect an engine as well as a hot 30 weight oil.

My state, Illinois, is a funny weather state. We have cold winters which sometimes get to -10°F and summers that get up to 105°F. Other states like Texas get hotter than Illinois. The point I am trying to make is that states with hot temperatures probably want to be using at least 5W-30 in the engines of vehicles there.

Anyway, I think we are all still learning. To me at least, it makes since that a lighter oil can lubricate better in that it can move more heat due to its thinness. But if the engine overheats which happens, can the film left by 5W-20 protect the engine? Here is a quote which really makes me wonder this...

http://www.machinerylubrication.com/article_detail.asp?articleid=518&relatedbookgroup=Maintenance

"In other words, an SAE 20 at 190°F is about the same kinematic viscosity as an SAE 30 at 220°F, which is about the same viscosity as an SAE 40 at 240°F. This approximation works well in the 190°F to 260°F temperature range. One might be surprised at the slight amount of difference between straight viscosity vs. multiviscosity oils with the same back number (for example, SAE 30, SAE 5W-30, and SAE 10W-30).

If an SAE 50 oil at 260°F is as thin as an SAE 20 oil at 190°F, imagine how thin the oil film becomes when you are using an SAE 5W-20 and your engine overheats. When an engine overheats, the oil film becomes dangerously thin and can rupture."
 
5W-20 and 5W-30 are both the same viscosity at room temp. They both start with the same base oil--what we designate 5W. The additives that turn it into a 20 or 30 only do so at warmer temps. The additives are little (plastic like) molecules that "unstretch" at warmer temps. When they do so, they "grab" the nearby oil molecules (which are smaller) and thus "thicken" the oil. (BTW, "shearing" is when these large molecules break and no longer "grab" the smaller oil molecules.)

At room temp, when the plastic-like molecules are not spread out, the oils from a can of 5-20 and 5-30 should run the same.
 
I am amazed that this thread is still going, but I am pleased that it hasn't turned into one of those threads that remind me of monkeys throwing crap at each other. Well done guys!
 
quote:

Originally posted by GMorg:
I am amazed that this thread is still going, but I am pleased that it hasn't turned into one of those threads that remind me of monkeys throwing crap at each other. Well done guys!

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This really makes it confusing, And makes no sense.
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quote:

Another way of looking at multi-vis oils is to think of a 20W-50 as a 20 weight oil that will not thin more than a 50 weight would when hot.

From here :http://auto.howstuffworks.com/question164.htm
 
quote:

Originally posted by sinker73:
5W-20 and 5W-30 are both the same viscosity at room temp. They both start with the same base oil--what we designate 5W. The additives that turn it into a 20 or 30 only do so at warmer temps. The additives are little (plastic like) molecules that "unstretch" at warmer temps. When they do so, they "grab" the nearby oil molecules (which are smaller) and thus "thicken" the oil. (BTW, "shearing" is when these large molecules break and no longer "grab" the smaller oil molecules.)

At room temp, when the plastic-like molecules are not spread out, the oils from a can of 5-20 and 5-30 should run the same.


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Holy Sweet good grief !!
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The above quoted post does not belong in this forum.
 
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