Shear Stability-ACEA A3

[buster]

Just bc an oil has an A3 rating doesn't mean it's more shear stable then one that doesn't. Mobil 1 0w-40 relies on VII's and has a HT/HS of 3.6, A3 rated. But an oil like Mobil 1 10w-30 or 0w-20 is much more likely to stay in grade then the 0w-40. This has been talked about before. So just because your using an A3 rated oil, doesn't mean everything. Agree, disagree?

If the new M1R uses a higher quality base oil, and less SS PAO, they would be able to achieve higher shear stability by relying on the thicker base stock. Does anyone think this is what they are doing with this new oil? I borrowed this from TS awhile back.

quote:

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Mobil 1 uses a relatively inexpensive, 3 or 4 Cst, PAO basestock which is thickened using the high vis. supersyn PAO - the SS takes the place of a conventional VI modifier. This makes for a very shear stable formulation, but does little for wear protection or volatility at high temps.

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[ February 01, 2004, 11:56 AM: Message edited by: buster ]

 

[buster]

The middle ground IMO is to have an oil with little or no VII's that is shear stable. Such as a Redline 10w-30. Delvac 1 is shear stable even though it's a 5w-40 bc it uses a better base stock. I think that is what we will (hopefully) find with the new M1R. I'd rather run a M1 10w-30 then a 0w-40 even though the 0w-40 has a HT/HS of 3.6 vs 3.2 for the 10w. However, if you need the extra high temp protection of the 40wt, then that is better.

 

[VeeDubb]

Heyjey,
Thanks for the info. If an oil meets A5, does it matter if it meets A3 from a practical perspective? In the wording, it seems the A3 gets a little more emphasis on "year-round use" which I interpret as having a large spread? So are there any real advantages to A3 over A5 or does A5 supersede A3?

Pedro,
Even though shearing occurred in the Valvoline I used, the wear rates were still very good. So for me, it wasn't about wear protection; it's about my concern that too much shearing can increase varnish which leads to a dirty engine and ring sticking in the long run.

 

[G-MAN]

quote:

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Originally posted by buster:
If the new M1R uses a higher quality base oil, and less SS PAO, they would be able to achieve higher shear stability by relying on the thicker base stock. Does anyone think this is what they are doing with this new oil?

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If this oil isn't just regular 0w30 with more addities, I think the "secret" behind it is the same thing that can be found in the product description of Mobil 1 15w50: It has more SuperSyn in it. The SuperSyn PAO comes in lower vis grades, too, so Mobil may have derived this racing formula from a blend of various SuperSyn PAO grades, with very little (if any) conventional PAO.

The more I think about it, the more that makes sense, actually. Again, remember: Mobil 1 trumpeted the "SuperSyn formula" as having been developed in conjunction with racing. I believe this "trick" PAO that George has been told about by someone at Mobil is nothing more than SuperSyn PAO. If this Mobil 1R is not just regular 0w30 with more ZDDP, it's probably a "Super SuperSyn" Mobil 1, i.e., the one grade of Mobil 1 that is built entirely with the SuperSyn PAO.

 

[buster]

quote:

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the one grade of Mobil 1 that is built entirely with the SuperSyn PAO.

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Very good point. I don't know when George was told about this. I do think it's likely that the base oil is more SS or a higher quality one. I just can't seem believe that such a high percentage of these racers are using a boosted M1 0w-30 with a HT/HS of 3.0. Don't buy it.

 

[moribundman]

Not all A3 oils are the same. Often manufacturers have additional demands. For example, VW 502/505 specs require additional testing in VW gas/diesel engines. The VW 502 spec requires high temp/high load testing in a 248 hour test during which no makeup oil must be added. There is also a limit on how much an oil's viscosity may increase.

 

[heyjay]

quote:

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Originally posted by VeeDubb:
Heyjey,
Thanks for the info. If an oil meets A5, does it matter if it meets A3 from a practical perspective? In the wording, it seems the A3 gets a little more emphasis on "year-round use" which I interpret as having a large spread? So are there any real advantages to A3 over A5 or does A5 supersede A3?

Pedro,
Even though shearing occurred in the Valvoline I used, the wear rates were still very good. So for me, it wasn't about wear protection; it's about my concern that too much shearing can increase varnish which leads to a dirty engine and ring sticking in the long run.

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A3 and A5 are intended for different applications, and the detailed explanation offered by ACEA - which BTW is public domain - goes into about 6 pages of detailed test specs. A5 does not supercede A3 or v-v. Different applications.

I guess if you want a "heavy duty" gasoline oil, A3 might be a better bet. For all-around use a A1/A5 might be fine. Remember these specs far exceed the API/SAE "Starburst."

Also remember that European makers can and DO have their own unique requirements. Folks in North America who gaze at the endless sea of "Starburst" oils at Partz R Us probably can't understand how/why an auto maker has such a SHORT "short list" of approved oils.

So there are "minimum" A3 oils and "better" A3 oils. You have to ask for the VOA and ACEA test results to determine this. A UOA after extreme use will also tell you how well the oil behaves in use.

Mobil Delvac 1 5W-40 and , hopefully, Mobil 1 Truck and SUV 5W-40, appear to use a superior basestock and superior additive package. Mobil 1 15W-50 also appears to use a superior basestock and superior additive package. I like these oils have have no problem using them in most of my vehicles.

So here is my question, hope it isn't too far off topic:

I'm actualy wondering if Mobil 1 15W-50 would be appropriate for a 2000 GMC Sierra with the Vortec 5.3 truck motor?

The Vortec 5.3 is based on the LS-1, and folks who run them very hard have used 15W-50 no problem. Certainly not in cold weather, that's why I use Mobil 1 0W-30, but say in hot summer, especially towing??

Or would I be better off with the "lighter" Mobil 1 Truck and SUV 5W-40 in summer?

Jerry

 

[VeeDubb]

quote:

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Originally posted by buster:
Just bc an oil has an A3 rating doesn't mean it's more shear stable then one that doesn't. Mobil 1 0w-40 relies on VII's and has a HT/HS of 3.6, A3 rated. But an oil like Mobil 1 10w-30 or 0w-20 is much more likely to stay in grade then the 0w-40. This has been talked about before. So just because your using an A3 rated oil, doesn't mean everything. Agree, disagree?

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Agree. I used Synpower 5w-40 which is A3 and meets a couple of VW 50X specs. It sheared from 82 down to 64.7 in a 5k interval. A 20% viscosity loss distrubs me. Now running GC.

Even though GC seems shear stable, I couldn't explain why my MPG jumped up by an average of 2-3 MPGs between 1000-2000 miles into the interval. Now I'm wondering if it also shears and then thickens again. TooSlick mentioned a while back that some oils are designed to shear and then thicken again to pass some of these tests. So

I just bought 4 quarts of Mobil 1 5w-30. It's only A1 but I bet it will be much more shear stable then Synpower I used which was A3.

 

[heyjay]

First, M1 5W-30 is rated A1/A5.

Quoting the ACEA A1: "Oil intended for use in gasoline engines specifically designed to be capable of using low friction, low viscosity
oils with a High Temperature / High Shear Rate Viscosity of 2.6 to 3.5 mPa.s. These oils may be unsuitable for use in some engines. Consult owner manual or handbook if in doubt."

Quoting the ACEA A5: "Stable, stay-in-grade oil intended for use at extended drain intervals in high performance gasoline engines designed to be capable of using low friction, low viscosity oils with a HT/HS of 2.9 to 3.5 mPa.s. These oils may be unsuitable for use in some engines. Consult owner manual or handbook if in doubt."

Quoting the ACEA A3: "Stable, stay-in-grade oil intended for use in high performance gasoline engines and / or for extended drain intervals where specified by the engine manufacturer, and / or for year-round use of low viscosity oils, and/or for severe operating conditions as defined by the engine manufacturer."

For A3, the shear stability test is based on the sequence 1.2 lab test called CEC-L-14-A-93, using a Bosch injector to severly shear the oil. They test at 100 C for 30 cycles. The A3 "All grades to be stay in grade."

For A3, the high temp shear (HTHS) is based on the sequence 1.3 lab test called CEC-L-36-A-97, or the Ravenfield. The result is in mPa s with a shear of one million shears per second at 150 C. Minimum value is 3.5 mPa s @ 150 C.

Here is an interesting quote about the viscosity grade, which ACEA loosly bases on SAE J300: "
No restriction except as defined by shear stability and HT/HS requirements. Manufacturers may indicate specific viscosity requirements related to ambient temperature."

That is completely 180 degrees out of phase with the API/SAE nonsense of "one oil for all uses and all seasons" ie the "Starburst" certification.

Of course, there are A3 oils that perhaps meet the bare minimum and those that exceed the test.

So A3 is still light years beyond the API/SAE "Starburst" nonsense. Like a Brand X 69 cent a quart 5W-30 at Partz R Us.

Jerry

 

[pruizgarcia]

Now you guys got me wondering again, so excuse my ignorance. You are saying that a shear stable oil does not necessarily equate to good wear protection or good volatility at high temps? A VI enhanced oil would do a better job at wear protection even if it is not very shear stable? What is the middle ground we should look for in seeking adequate shear stability and wear protection. Thanks.

Pedro

[ February 01, 2004, 12:52 PM: Message edited by: pruizgarcia ]