Quote:
So, relative to an A3/B3 oil, an A3/B4 10W40 will contain...
...more metallic detergent (for TBN)
...more ashless dispersant (for Tdi)
...more Group III (for TU5)
...less VII polymer
Thanks Joe, I always enjoy reading your posts.
What you say certainly makes sense when picking between 10W40 semi-synthetics, the A3/B4 is the better pick. Over here all our 10W40's are A3/B4 anyway, and some like Shell also carry some OEMs like MB 229.3 and yes all carry SN as well.
To me the big choice is a full synthetic 5W-40 A3/B4 (probably Group III) or a mineral 15W-40 A3/B3 (probably Group II). These are the two most common 40 grade offerings around here and both are also SN.
Now apart from price, which is a significant difference, and TBN. The Group III will have a higher natural VI, but it's a 5W product. The Group II will have a lower VI, but it's a 15W. So which would carry the higher VII load ?
The A3/B4 has to pass Tdi with cleaner pistons, but it's a Group III oil. The A3/B3 has a lower Tdi clean piston requirements, but it's a Group II. So which needs more ashless dispersants ?
Which would you expect to have the lower Noack ?
My confusion is that in my market, the higher spec A3/B4 goes with the higher quality base (Group III) and the much higher price tag. The lower spec A3/B3 is always a mineral oil for me and much cheaper. But if I'm doing reasonable OCI's like 6k miles on the mineral and 9k miles on the synthetic, I suspect I may be getting more oil for my money buying the cheaper mineral oil. The mineral is easily have the price of the synthetic, but is it half the oil ?