Difference between A3/B3 and A3/B4?

[SonofJoe]

Originally Posted By: Shannow
No probs..

there's been a meme for a long time on the board that synthetics (like TGMO 0W20, or Mobil Racing 0W50 with it's 3.7HTHS) get their "0W" rating "by accident" as a result of their superior ingredients.

The 15W therefore strikes me as a bit odd, given that if it met 10W or 5W it must be labelled as such.



I do understand what you're staying here. I can't honestly recall ever having tried to make a full PAO 15W40 so you may well be right.

However if memory serves, a typical Euro Group I 15W40 might contain about 7-8% liquid OCP VII. By switching from Group I to PAO you're going to up the aggregate base oil VI from say 100 to 130 which is good, but 7-8% of VII represents a lot of VI to displace. My gut feel would be that a reasonably viscometrically tight full PAO 15W40 should be doable.

 

[1JZ_E46]

I wonder how much of it has to do with marketing. I.e. oil refiners making “0W” racing or high performance oils because it sounds like a premium product, even though it’s not an ideal target. 0W oils have typically been top of the line products due to the quality of base oil needed to meet the 0W specs. If they came out with a 5W or 10W oil that was better in every way (assuming proper climate), customers may believe it is inferior simply because of its SAE grade. Hopefully that makes sense. 0W-50 seems wholly unnescessary, and I’m sure it recquires VII to get there.

 

[Shannow]

Originally Posted By: 1JZ_E46
0W-50 seems wholly unnescessary, and I’m sure it recquires VII to get there.


Here's the data...
https://www.mobil.com/english-us/passenger-vehicle-lube/pds/glxxmobil-1-racing-oils

It's a sully unicorn - "50" grade with 3.8 HTHS...would be better off with something like Redline 5W30, or M1 Racing 4T 10W40.

 

[Popsy]

Maybe it’s just an « exercice de style », a way for Mobil to show of, or to prove their technical advance in oil base or whatever?
There are only two 0W50 on the market (I think)...I agree it’s a pretty useless, but still sounds

 

[SR5]

Quote:
would be better off with .... M1 Racing 4T 10W40

I agree or the M1 20W50 V-Twin

 

[SR5]

So going back to 40 grade full synthetics, I can't recall any 15W40 full synthetics in shops around me, but I have seen a few full synthetic 10W-40s.

There is M1 10W40 HM that is SN & A3/B3
Nulon 10W-40 Full Synthetic that is SN & A3/B4 & VW 502/505 (claim).

How "good" are these full synthetic 10W40s ?
It seems to me the Group II 15W40 is a natural oil grade in that it has lots of natural benefits, as Joe has already pointed out, would these natural benefits carry across to a Group III or IV 10W40 ?

Looks to me like I should buy either mineral 15W40, then skip the 10W40 semi-synthetics, and go straight to the 40 grade full synthetics - of which I would expect the 10W40 to be one of the better ones.

 

[SilverFusion2010]

M1 15w-50 has HTHS of 4.5

 

[Seventh]

Originally Posted By: SilverFusion2010
M1 15w-50 has HTHS of 4.5


https://www.mobil.com/English-US/Passenger-Vehicle-Lube/pds/NAUSMobil-1-15W50

And it's A3/B3 rated. PDS also says it's ok for diesel but only mentions CF?

 

[SR5]

Originally Posted By: Seventh
Originally Posted By: SilverFusion2010
M1 15w-50 has HTHS of 4.5


https://www.mobil.com/English-US/Passenger-Vehicle-Lube/pds/NAUSMobil-1-15W50

And it's A3/B3 rated. PDS also says it's ok for diesel but only mentions CF?


Maybe they are referring to the ACEA B3 which is for light duty passenger car diesel engines, that are very common in Europe.

 

[SonofJoe]

Originally Posted By: Seventh
Originally Posted By: SilverFusion2010
M1 15w-50 has HTHS of 4.5


https://www.mobil.com/English-US/Passenger-Vehicle-Lube/pds/NAUSMobil-1-15W50

And it's A3/B3 rated. PDS also says it's ok for diesel but only mentions CF?



This is interesting. On the spec sheet is lists API approvals as SN, SM, SL & SJ. However it lists API CF separately with a 'According to ExxonMobil, Mobil 1 15W50 is of the following quality' caveat.

API CF is now officially dead, so either they have a passing Cat 1MPC and are not declaring CF as an official approval, or they never passed the Cat 1MPC in the first place and are now doing 'the spec's dead so we can say whatever we want to' thing.

Like most diesel tests, the Cat 1MPC was always very sensitive to the amount of VII in the oil and I could imagine even an all synthetic 15W50 might not be a walk in the park.