ACEA A1/B1 only, or is A5/B5 better?

[ColdCranker]

I see some oils have an ACEA A1/B1 rating, and some can manage to get A5/B5 on top of that. For example, the new Mobil1 EP 5w-30 gets A1/B1 and A5/B5, while the Mobil1 5w-30 only gets A1/B1. Does this mean it failed the A5/B5 or was it never tested to that? If my hunch is correct, the ACEA A5/B5 can separate the men from the boys. Those tests are brutal.

 

[shanneba]

What do find that is "brutal" about the A5/B5 spec? A1/B1 and A5/B5 are both less than 3.5 in HTHS. A3/B3 or A3/B4 are both >3.5 HTHS.

 

[bar1]

M1 5W-30 doesn't fit the requirement for A5/B5 and was probably designed that way. A1/B1 - HTHS 2.6 - 3.5 A5/B5 - HTHS 2.9 - 3.5 What is "best" depends on what is recommended for your engine.

 

[AndyH]

Info from ACEA:

quote:

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A1/B1 Oil intended for use in gasoline and car + light van diesel 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 mPas.s. These oils may be unsuitable for use in some engines. Consult owner manual or handbook if in doubt. A3/B3 Stable, stay-in-grade oil intended for use in high performance gasoline and car + light van diesel 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. A3/B4 Stable, stay-in-grade oil intended for use in high performance gasoline and direct injection diesel engines, but also suitable for applications described under B3. A5/B5 Stable, stay-in-grade oil intended for use at extended drain intervals in high performance gasoline and car + light van diesel engines designed to be capable of using low friction low viscosity oils with a High temperature / High shear rate viscosity 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.

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[glxpassat]

What is the ACEA definition of the A2 rating?

 

[Paranoil]

ACEA A2 (Feb 2002) A2 General purpose oil intended for use in most gasoline engines with normal drain intervals, although it may not be suitable for some high performance engines.

 

[AndyH]

To add to what Paranoil wrote, according to the 2004 ACEA Oil Sequences document I have the A2 rating sounds like it's been eliminated:

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The categories A2 and B2 are not included in this edition of the ACEA European Oil Sequences because they are unsuitable for some of the current engines and will be unsuitable for many future engines. Misuse may cause engine damage. However, the use of A2/B2 oils for older engines (where owner's or workshop's literature recommends this use) is still appropriate and can be done according to the categories A2-96 Issue 3 and B2-98-Issue 2.

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[glxpassat]

I just found a dated pdf that stated that an A2 is supposed to have a minimuim HTHS of 3.5, like the A3 spec.

 

[ColdCranker]

shanneba and AndyH, What is brutal about A5/B5? I was remembering an http://www.swri.org website, from a company that sells ACEA test services to oil companies, that essentially showed engines being run in week-long continuous running at/near redline, and then checked for ring sticking, cam scuffing, etc. It seems it separates the men from the boys in motor oils, and was wondering whether this is really the case. It is suspicious that Mobil1 EP 5w-30 has both A1/B1 AND A5/B5, while Mobil1 0w-40 has A3,B3/B4 ratings. It makes you wonder if the 0w-40 is wimpier than the EP 5w-30 product.

 

[ColdCranker]

In a nutshell, what would really be great to know is: What test (maybe ACEA) really stresses the sh*t out of motor oils, to indicate what oil really stands up best. The confusing mish-mash of ratings (see http://www.mobil1.com/USA-English/MotorOil/Oils/Mobil_1_0W-40.aspx for one example, and compare with other Mobil1 flavors ) really needs some light shed on it, IMHO. For example, I hear that "SM" really is easy to pass, so that leaves a bunch of other stuff to look at. Is the GM test tougher than the BMW one? Mainly concerned about which oil prevents wear the best, and prevents rings from sticking, etc., related to engine longevity. I'll forego "energy saving" tests, since most of that is due to viscosity anyway, and the difference in fuel economy is probably negligible anyway.

 

[akuska]

quote:

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It is suspicious that Mobil1 EP 5w-30 has both A1/B1 AND A5/B5, while Mobil1 0w-40 has A3,B3/B4 ratings. It makes you wonder if the 0w-40 is wimpier than the EP 5w-30 product.

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I'm not sure what you mean. A5 specifically says it is for engines "designed to be capable of using low friction low viscosity oils." How would a 40-weight ever be considered "low friction" or "low viscosity"? It seems to me that A5>A1, but that A5 and A3 are different categories. Higher numbers aren't necessarily intended to mean better.

 

[AndyH]

Coldcranker: More info in this PDF from ACEA: ACEA 2004 Sequences

 

[oilyriser]

C Syntec and V Synpower 5w30 both say A1 and A5.

 

[ColdCranker]

AndyH, You're the greatest. Good link there. From reading it, it looks like the A1/A5, B1/B5 requires a higher HTHS property. From a previous Southwest Research Institute document (people who do the ACEA tests) I saw a while back, the RPMs are high during much of the ACEA tests. akuska, It looks like the higher ACEA numbers are maybe slightly tougher than the lower numbers, from AndyH's web link document.

 

[ColdCranker]

What is the baddest-a** test there is? Wear, rings sticking, but not so much energy saving. I really wish they would just take 10 identical engines, fill them with GC 0w-30, then take 10 more of the same engines, fill them with M1 EP 5w-30, then maybe 10 more with M1 0w-40. Now, run the engines, without adding any oil, at 90% of redline until the engines stop. Who would be left standing? I call it the "A2Q3G5'tilUpuuck" test.

 

[akuska]

ColdCranker, I'm not entirely sure I agree with the assessment that A5/B5 > A3/B3. Perhaps someone could explain the HTHS rating in better detail, but it seems that A1 and A5 seem to allow a maximum HTHS right where A3 starts off at the minimum. Doesn't a higher HTHS imply less loss at high speeds and high temperatures? Note that both the descriptions for A1/B1 and A5/B5 state quite clearly that they "may not be suitable for certain engines" while that is not the case for A3. A1/A5 also have to meet the fuel consumption standard, which is why they have the lower HTHS ratings.

 

[ColdCranker]

akuska, ACEA confuses me a little, but I think higher HTHS keeps a tougher oil film on the metal under the stress of high loads, temperatures. Higher HTHS is desirable.

 

[akuska]

Exactly. Doesn't that imply that ACEA A3 provides more protection under higher loads and higher temperatures?

 

[palmerwmd]

quote:

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Originally posted by akuska: Exactly. Doesn't that imply that ACEA A3 provides more protection under higher loads and higher temperatures?

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It would appear so.

 

[Roger]

In addition to the HTHS differences cited, A5 oils also call for greater shear stability, lower NOACK levels, allow for more Ash content in oil, and provide for some differences in engine testing (which I don't profess to understand). A5 oil is also considered suitable for "extended drains" by ACEA, where A1 oil is not. On paper at least, A5 oils are a tad bit better than A1. Like M1 EP 5W30, regular Mobil 1 10W30 is A1/A5 too.