quote:I don't hold much value in the "50% rule" when it comes to TBN. If one oil starts out with a TBN of 7 and then it drops to 4 (still not 50%), but you have another oil that starts out at 12 and drops to 6, which one would you rather have in your engine? I'd rather have the one with 6, even though it has dropped 50% and the other one has dropped less. But that's just me.
Originally posted by Spector: It appears that it is more important in how quickly the TBN drops to 50% of its original value rather then how high it is to begin with. A TBN of 12 that drops to 6 in 3000 miles to me is not as good as a TBN of 8 that drops to 6 after 3000 miles. The later is doing a better job it seems
Quote:It's difficult to judge tbn retention in the uoa forum because half the oil reports didn't get the tbn test. Would you say worst to best is: 6. dino energy conserving 5. syn blend energy conserving 4. dino non-energy conserving 3. syn blend non-energy conserving 2. synthetic 1. mixed fleet Or, are there certain brands that retain tbn better than others? I did see Havoline Deposit Shield has a low tbn # in two oil reports.
Patman, I'd go with the first one 7 to 4 tbn over the other one of 12 to 6. The 7-4 drop was a lot slower and had a better antioxidant package which is protecting it from acids by neutralizing the acids before build up, therefore it isn't relying as much on the detergents to clean up as much, unlike the other 12-6 it relys on the detergents more to clean up the acids and will continue to break down at a faster rate as the acids are not being neutralized prior to causing base oil attack.