how important is TBN

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Does it mean higher TBN=more detergent? Why do some race oils have a high TBN. Kendall 40w=6.5 and Valv 40w=12
 
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If you are doing short drain intervals TBN is not really of a big concern. If you are extended drains, or if you are running a diesel, you need enough TBN to prevent acid build in your oil caused from the combustion process.
 
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Can somebody define the term "Extended Drain" ? Would you consider 7500 mile drains in car that sees 90% highway miles (65-75 mph/2800-3200 rpms) extended? Thanks!
 

Patman

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Everyone's idea of an extended drain might be different, but to me, anything at 6k or higher is an extended drain. Between 3-6k I would consider it a slightly extended drain, but that's just my terminology! [Razz]
 
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Bobistheoilguy (or in California Bobisthelubedude) explained to us that TBN is often relative Some oils go through their TBN quicker and each individual's car is also a variable The best way to see if the TBN in your selected oil is ok is to run an analysis [ August 09, 2002, 09:43 AM: Message edited by: jjbula ]
 

MolaKule

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To me, an "extended drain" is any drain interval past the industry 3k drain interval for regular dino oil.
 
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Dodge/Honda recommend 7500 miles. VW TDI says 10,000 miles. I call that "normal." Anything past that is "extended." i.e. Extended beyond the manufacturer's recommendations. Troy
 

MolaKule

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OK, maybe I should have been more specific. With respect to major oil company hype, an extended drain is any drain interval beyond the previously accepted/recommended 3k drain interval.
 
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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
 

Patman

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quote:
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
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. [Smile]
 
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I think I understand what your saying Patman. I think what Bob & Spector are trying to say is that, the oil with TBN 7 is much more stable, and better at acid neutralization than the oil with TBN 12 because the drop in TBN is much lower, even though they both dropped 50% (provided both have the same mileage). Kinda like how 5W30 is much more stable and requires less VI improvers than 5W50. Bob, I hope this is what you were trying to convey... [Smile] Oz
 

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OK, but let me put it another way. Why do people say to change the oil when the TBN is at 2, or at half it's original value? Why can't it just be standard across the board to change any oil when it reaches 2?
 
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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.
 

Patman

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But let's say this drop occured over a 10,000 mile interval. Wouldn't the one with the finishing TBN of 6 still be doing a better job all along since the entire time this oil is in there it's still at a higher TBN than the other oil here? Am I making sense? [Big Grin]
 
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Thanks, did it purposely to see who would be the first to make a comment like that! CONGRATULATIONS!!!!
 
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Quote:
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.
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.
 
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