ACEA Question

[Francis]

I have heard in this site that the SL ratting is not all the great in terms of Performance grading and it doesn't take much to meet it. SO I was just wondering if oil is ACEA A3 B3 would this be a good measure of a quality oil, or base oil or it's over all performance, or is it also not much to go by?

 

[sbc350gearhead]

ACEA A3 spec, is probably one of the best specs for an oil..........in the 30 and 40 weights. The heavier the oil........the easier it is to meet this spec (at least that is the way it looks to me). The A3 spec is not a make it or break it spec. Mobil 1 30 weights are excellent and do not meet it.

 

[2KBMW]

Francis. The A3 spec relates to a certain thickness of the oil at 150 deg. C. (HT/HS value). IF an oils thickness is greater than 3.5 at 150 C, then it will be A3. If it's less than 3.5 ie. 3.17 for mobil 1 10w30, then it will be certified A5. Both these oils are also long life or drain oils where an oil rated A1 is not. These A3 oils in the 5w/10w30 grades are not better than other oils in the same grade,only thicker. Where an oil may be the highest quality is in the case of a 5w40 or 15w50 grade. These will be A3 of course but have a higher or better additive package. This is only the way I understand it. I'm sure the oil gurus will add to this or correct me if I'm wrong.

 

[G-MAN]

quote:

---

Originally posted by 2KBMW: Francis. The A3 spec relates to a certain thickness of the oil at 150 deg. C. (HT/HS value). IF an oils thickness is greater than 3.5 at 150 C, then it will be A3. If it's less than 3.5 ie. 3.17 for mobil 1 10w30, then it will be certified A5. Both these oils are also long life or drain oils where an oil rated A1 is not. These A3 oils in the 5w/10w30 grades are not better than other oils in the same grade,only thicker. Where an oil may be the highest quality is in the case of a 5w40 or 15w50 grade. These will be A3 of course but have a higher or better additive package. This is only the way I understand it. I'm sure the oil gurus will add to this or correct me if I'm wrong.

---

There are over a dozen different test parameters that an oil must pass to be rated either A3 or A5. It's not just about the HT/HS numbers. The only difference between A3 and A5 IS the HT/HS, which you have correctly stated. An A3 oil must have an HT/HS of >3.5. An A5 oil must have an HT/HS of <3.5.