I am curious what the difference between A3/B4 and A5/B5 is. I see A3/B4 talked about more often on this site. It seems to get recommended quite a bit so I checked out my Castrol Edge and PUP and both Show A5/B5. Following standard number schemes this sounds like the better option, so why is it not recommended as much?
A3/B4 vs A5/B5
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A5/B5 have lower minimum HTHS than A3/B3 and A3/B4.
https://www.lubrizol.com/EngineOilAdditives/ACEA/Sequences/ACEA-A5B5-10.html
https://www.lubrizol.com/EngineOilAdditives/ACEA/Sequences/ACEA-A5B5-10.html
A3/b4 is for high HT/HS applications. Not better or worse. Just different requirements. Apples to oranges. With ACEA specs, higher number does not mean better.
Hi Mate,
Here is a link to the ACEA sequences:
http://www.acea.be/uploads/publications/2012_ACEA_Oil_Sequences.pdf
The biggest difference between A3/B3 and A5/B5 is HTHS. For A5 it's a min of 2.9 and a max of 3.5 but for A3 the HTHS must be above 3.5 (or equal at a min). So with A3 oil you have a thicker & stronger oil but at a minor cost to fuel economy. ILSAC 5W-30 synthetics typically have a HTHS of 3.0 to 3.1, so they must be A5. Euro oils for BMW & MB require a min HTHS of 3.5, so they must be A3.
The biggest difference between A3/B3 and A3/B4 is TBN. The A3/B3 needs a TBN of 8 or more, while a A3/B4 requires a TBN of 10 or more (similar to a EP oil).
All ACEA oils are also required to pass a shear stability - stay in grade test, which requires the use of high quality shear stable VII polymers.
So when you say a A3/B4 oil, you are really saying a high quality, shear stable oil, with a high HTHS (min 3.5) and a high TBN (min 10). A very robust oil.
When you say A5/B5, you are saying a high quality shear stable oil, that is also resource conserving. It will have a min HTHS of 2.9 and a min TBN of 8.0 which is fine for many regular applications.
Here is a link to the ACEA sequences:
http://www.acea.be/uploads/publications/2012_ACEA_Oil_Sequences.pdf
The biggest difference between A3/B3 and A5/B5 is HTHS. For A5 it's a min of 2.9 and a max of 3.5 but for A3 the HTHS must be above 3.5 (or equal at a min). So with A3 oil you have a thicker & stronger oil but at a minor cost to fuel economy. ILSAC 5W-30 synthetics typically have a HTHS of 3.0 to 3.1, so they must be A5. Euro oils for BMW & MB require a min HTHS of 3.5, so they must be A3.
The biggest difference between A3/B3 and A3/B4 is TBN. The A3/B3 needs a TBN of 8 or more, while a A3/B4 requires a TBN of 10 or more (similar to a EP oil).
All ACEA oils are also required to pass a shear stability - stay in grade test, which requires the use of high quality shear stable VII polymers.
So when you say a A3/B4 oil, you are really saying a high quality, shear stable oil, with a high HTHS (min 3.5) and a high TBN (min 10). A very robust oil.
When you say A5/B5, you are saying a high quality shear stable oil, that is also resource conserving. It will have a min HTHS of 2.9 and a min TBN of 8.0 which is fine for many regular applications.
So next question, What about A1/B1?
I noticed this on the back of my Castrol Edge bottle.
I noticed this on the back of my Castrol Edge bottle.
A1/B1 & A5/B5 are much the same ( I think A5/B5 is a little better) they both have a TBN min of 8.0 and the same HTHS limits for 30 weight and above oils ( 2.9 to 3.5).
But A1/B1 allows 20 weight oils (xW-20) to have a lower HTHS min of 2.6, for example M1 AFE 0W-20 has a HTHS of 2.7, so it can be A1/B1 but not A5/B5. Not saying it is A1/B1 or not.
I'm a robust & long life oil sort of guy, so I look for A3/B4, high HTHS and high TBN. Belts and braces please.
But if I wanted a ILSAC style of oil, A5/B5 would be my minimum (I think it's a little better than Dexos - which is still a great standard). You can keep my share of the A1/B1 xW-20 oils, maybe I'll keep a little for my wife's sewing machine.
But A1/B1 allows 20 weight oils (xW-20) to have a lower HTHS min of 2.6, for example M1 AFE 0W-20 has a HTHS of 2.7, so it can be A1/B1 but not A5/B5. Not saying it is A1/B1 or not.
I'm a robust & long life oil sort of guy, so I look for A3/B4, high HTHS and high TBN. Belts and braces please.
But if I wanted a ILSAC style of oil, A5/B5 would be my minimum (I think it's a little better than Dexos - which is still a great standard). You can keep my share of the A1/B1 xW-20 oils, maybe I'll keep a little for my wife's sewing machine.
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