Does anyone actually know what happens to an engine if the TBN goes below 1.0 for say 3K miles? Say you had an OCI of 10K, like myself, and did a used oil analysis and it showed a TBN of 1.0,(everything else was fine in the report) but decided to extend the OC to 13K. Does anyone have real world experience with this sitution, not the spectulation we may assume? You what assume means.
Speaking of TBN
- Thread starter tig1
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I don't know the mechanics of it. My sister just replaced the engine in her Mazda 3 after not changing the oil for "a year and a half", so probably that. The engine was making loud enough noises that finding the real problem wasn't really necessary.
By the time TBN gets to 1.5 TAN could be 4.8 (real life experience for me) and the oil was done for, several thousand miles previously. Many people think the oil is done when TAN>TBN. Sometimes typical STARTING TANs are 2.5, and they go up from there.
In the above scenario I had Fe of 99ppm, admittedly a relatively new (10 to 20K mile interval) car still breaking in.
But you can see why I'm not fond of ESP MB229.51 type oils which have a starting TBN of 6.4. So I switched to Delvac 1 LE 5W30, TBN 12.6, P Because of the TAN>TBN cutoff, an oil of double the starting TBN may have triple or quadruple the useful life of a low TBN oil, based on TBN-TAN relationship.
Detroit Diesel in its' user literature on lube oils recommends a TBN condemnation number of 33% of starting, or 3.0, whicher comes 1st, NOT 1.0!
Charlie
In the above scenario I had Fe of 99ppm, admittedly a relatively new (10 to 20K mile interval) car still breaking in.
But you can see why I'm not fond of ESP MB229.51 type oils which have a starting TBN of 6.4. So I switched to Delvac 1 LE 5W30, TBN 12.6, P Because of the TAN>TBN cutoff, an oil of double the starting TBN may have triple or quadruple the useful life of a low TBN oil, based on TBN-TAN relationship.
Detroit Diesel in its' user literature on lube oils recommends a TBN condemnation number of 33% of starting, or 3.0, whicher comes 1st, NOT 1.0!
Charlie
Originally Posted By: m37charlie
So I switched to Delvac 1 LE 5W30, TBN 12.6,
Do you know what the starting TAN is for this oil by any chance?
Quote:
Many people think the oil is done when TAN>TBN
Yeah. Actually, the lab I use has a general rule of thumb that when the TAN is 80% of the TBN, the oil should be changed, but I'm sure they err on the side of caution. They flagged my last 10K OCI report because TBN was 4.3 while TAN was 3.5. But anyway, sorry for this little OT...
So I switched to Delvac 1 LE 5W30, TBN 12.6,
Do you know what the starting TAN is for this oil by any chance?
Quote:
Many people think the oil is done when TAN>TBN
Yeah. Actually, the lab I use has a general rule of thumb that when the TAN is 80% of the TBN, the oil should be changed, but I'm sure they err on the side of caution. They flagged my last 10K OCI report because TBN was 4.3 while TAN was 3.5. But anyway, sorry for this little OT...
Originally Posted By: tig1
Does anyone actually know what happens to an engine if the TBN goes below 1.0 for say 3K miles?
No direct experience in this situation but IIRC once TBN starts to get low you should also measure TAN to determine what's actually going on with the oil.
Does anyone actually know what happens to an engine if the TBN goes below 1.0 for say 3K miles?
No direct experience in this situation but IIRC once TBN starts to get low you should also measure TAN to determine what's actually going on with the oil.
Originally Posted By: tig1
Does anyone actually know what happens to an engine if the TBN goes below 1.0 for say 3K miles? Say you had an OCI of 10K, like myself, and did a used oil analysis and it showed a TBN of 1.0,(everything else was fine in the report) but decided to extend the OC to 13K.
Apparently nothing happens, or at least nothing that can be deduced from a used oil analysis. Heck, the TBN never actually goes down to such low level...
http://neptune.spacebears.com/cars/stories/mobil1.html
http://neptune.spacebears.com/cars/stories/amsoil.html
Does anyone actually know what happens to an engine if the TBN goes below 1.0 for say 3K miles? Say you had an OCI of 10K, like myself, and did a used oil analysis and it showed a TBN of 1.0,(everything else was fine in the report) but decided to extend the OC to 13K.
Apparently nothing happens, or at least nothing that can be deduced from a used oil analysis. Heck, the TBN never actually goes down to such low level...
http://neptune.spacebears.com/cars/stories/mobil1.html
http://neptune.spacebears.com/cars/stories/amsoil.html
My TBN went to 1.5 with a TAN of 4.83. At ~10K miles, the prescribed OCI, Fe was 94.
The 2nd time, after 9K miles, TBN was again 1.5, they didn't measure TAN Fe was 83. This is at ~30K miles total.
The D1 LE with a VOA TBN of 12.6 i'd guess has a starting TAN of ~2.5
I plan to run it 12-14K miles and then do a used oil analysis. I anticipate a TBN around 6 and much lower Fe levels.
Charlie
The 2nd time, after 9K miles, TBN was again 1.5, they didn't measure TAN Fe was 83. This is at ~30K miles total.
The D1 LE with a VOA TBN of 12.6 i'd guess has a starting TAN of ~2.5
I plan to run it 12-14K miles and then do a used oil analysis. I anticipate a TBN around 6 and much lower Fe levels.
Charlie
As the motor oil becomes more acidic, it corrodes and degrades the metals. Making the oil into an acid is the same as pouring a weak acid over a metal. Ever put acid on a penny in high school, or left lemon juice sitting in a pan over night, or had a battery leak into a metal tray? The acids will oxidize the metal and destroy it. This process is very slow in an engine, but because the oil stays in the engine like this for weeks or months, it becomes a problem. I suspect that consistently high TAN would show up in an UOA as increased metals, especially Fe. Not all of the Fe would be destroyed or turned into gas (i.e. hydrogen) some would end up in the oil.
^Great point.
This makes me want to get a TAN during my next extended UOA. I'd really like to see what's up and compare wear numbers.
This makes me want to get a TAN during my next extended UOA. I'd really like to see what's up and compare wear numbers.
Originally Posted By: m37charlie
My TBN went to 1.5 with a TAN of 4.83. At ~10K miles, the prescribed OCI, Fe was 94.
The 2nd time, after 9K miles, TBN was again 1.5, they didn't measure TAN Fe was 83. This is at ~30K miles total.
The D1 LE with a VOA TBN of 12.6 i'd guess has a starting TAN of ~2.5
I plan to run it 12-14K miles and then do a used oil analysis. I anticipate a TBN around 6 and much lower Fe levels.
Charlie
However I once ran my old 96 Merc 4.6 to well over 10K and the TBN was down to .5 but my iron was only 20PPM and all the other metals were very good as well. This was with Mobil 1 High Mileage 10w30.
My TBN went to 1.5 with a TAN of 4.83. At ~10K miles, the prescribed OCI, Fe was 94.
The 2nd time, after 9K miles, TBN was again 1.5, they didn't measure TAN Fe was 83. This is at ~30K miles total.
The D1 LE with a VOA TBN of 12.6 i'd guess has a starting TAN of ~2.5
I plan to run it 12-14K miles and then do a used oil analysis. I anticipate a TBN around 6 and much lower Fe levels.
Charlie
However I once ran my old 96 Merc 4.6 to well over 10K and the TBN was down to .5 but my iron was only 20PPM and all the other metals were very good as well. This was with Mobil 1 High Mileage 10w30.
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^I wonder if the following OCI would have shown the presence of more wear or not?
Originally Posted By: tinmanSC
As the motor oil becomes more acidic, it corrodes and degrades the metals. Making the oil into an acid is the same as pouring a weak acid over a metal. Ever put acid on a penny in high school, or left lemon juice sitting in a pan over night, or had a battery leak into a metal tray? The acids will oxidize the metal and destroy it. This process is very slow in an engine, but because the oil stays in the engine like this for weeks or months, it becomes a problem. I suspect that consistently high TAN would show up in an UOA as increased metals, especially Fe. Not all of the Fe would be destroyed or turned into gas (i.e. hydrogen) some would end up in the oil.
Once again this example is not the same as in an engine. Most of the very high OCIs(15-20K) we see here on BITOG still show some TBN left. I personally believe we worry way too much about TBN as I still haven't seen what very low TBN does to an engine.
As the motor oil becomes more acidic, it corrodes and degrades the metals. Making the oil into an acid is the same as pouring a weak acid over a metal. Ever put acid on a penny in high school, or left lemon juice sitting in a pan over night, or had a battery leak into a metal tray? The acids will oxidize the metal and destroy it. This process is very slow in an engine, but because the oil stays in the engine like this for weeks or months, it becomes a problem. I suspect that consistently high TAN would show up in an UOA as increased metals, especially Fe. Not all of the Fe would be destroyed or turned into gas (i.e. hydrogen) some would end up in the oil.
Once again this example is not the same as in an engine. Most of the very high OCIs(15-20K) we see here on BITOG still show some TBN left. I personally believe we worry way too much about TBN as I still haven't seen what very low TBN does to an engine.
Originally Posted By: Quattro Pete
Originally Posted By: tig1
Does anyone actually know what happens to an engine if the TBN goes below 1.0 for say 3K miles? Say you had an OCI of 10K, like myself, and did a used oil analysis and it showed a TBN of 1.0,(everything else was fine in the report) but decided to extend the OC to 13K.
Apparently nothing happens, or at least nothing that can be deduced from a used oil analysis. Heck, the TBN never actually goes down to such low level...
http://neptune.spacebears.com/cars/stories/mobil1.html
http://neptune.spacebears.com/cars/stories/amsoil.html
I have viewed these reports as well and completely agree with you.
Originally Posted By: tig1
Does anyone actually know what happens to an engine if the TBN goes below 1.0 for say 3K miles? Say you had an OCI of 10K, like myself, and did a used oil analysis and it showed a TBN of 1.0,(everything else was fine in the report) but decided to extend the OC to 13K.
Apparently nothing happens, or at least nothing that can be deduced from a used oil analysis. Heck, the TBN never actually goes down to such low level...
http://neptune.spacebears.com/cars/stories/mobil1.html
http://neptune.spacebears.com/cars/stories/amsoil.html
I have viewed these reports as well and completely agree with you.
A low TBN also reduces the oil's detergency which leads to increased fouling within the engine.
Originally Posted By: Hallmark
A low TBN also reduces the oil's detergency which leads to increased fouling within the engine.
I have to agree. With a low / NO TBN, that means, there's very little active additives left. If there are little - NO additives remaining, the oil basically stops cleaning / neutralizing harmful contaminants, so basically, sludge begins to form.
I'm sure the oil can continue to lubricate the engine but build up of sludge starts to form.
A low TBN also reduces the oil's detergency which leads to increased fouling within the engine.
I have to agree. With a low / NO TBN, that means, there's very little active additives left. If there are little - NO additives remaining, the oil basically stops cleaning / neutralizing harmful contaminants, so basically, sludge begins to form.
I'm sure the oil can continue to lubricate the engine but build up of sludge starts to form.
^Which is why a used oil analysis helps to see if potential for sludge increases the closer to 1.0 the TBN gets(hand in hand with rise in TAN for wear concerns).
The primary reason for a used oil analysis, IMO, aside from monitoring potential problems like anti-freeze/fuel dilution/add pack...is the operating range. Is it within spec, desired range, or has it sheared too much.
The primary reason for a used oil analysis, IMO, aside from monitoring potential problems like anti-freeze/fuel dilution/add pack...is the operating range. Is it within spec, desired range, or has it sheared too much.
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