2005 BMW 645 7,305 Mi M1 0w40

[10cent]

We live in the city and this vehicle is used daily for trips of less than three miles. I've owned this vehicle since new and during the free maintenance period it received Castrol at intervals specified by the OLM. I have used Mobil 1 0w40 with roughly bi-annual intervals since the expiration of the free maintenance.

The oil was in service from August 2012 to March 2013 and was changed with ~2,700 miles left on the OLM.

With usage consisting of nearly exclusively short trips I was expecting to see more fuel dilution but I'm certainly not going to complain. I'm very pleased with these results and will likely extend to an annual or OLM specified OCI.

 

[OVERKILL]

Can you post a picture of what the cylinder head looks like under the oil fill cap?

 

[10cent]

Originally Posted By: OVERKILL
Can you post a picture of what the cylinder head looks like under the oil fill cap?


Sure. It'll likely be Saturday before I can get it done but I'll get one up here. If I remember correctly it looks directly at one of the timing chains and has always appeared to be clean.

 

[OVERKILL]

Originally Posted By: 10cent
Originally Posted By: OVERKILL
Can you post a picture of what the cylinder head looks like under the oil fill cap?


Sure. It'll likely be Saturday before I can get it done but I'll get one up here. If I remember correctly it looks directly at one of the timing chains and has always appeared to be clean.


Yes, it should be a similar view to mine on my S62 (you have an N62), if you get the angle right you can see a bit of the head, though not much.

 

[Quattro Pete]

You guys are lucky... I can't see a darn thing when I look under the oil cap because of the baffle.

 

[OVERKILL]

Originally Posted By: Quattro Pete
You guys are lucky... I can't see a darn thing when I look under the oil cap because of the baffle.


Yeah, I noticed that with the 328i, it sucks!!!

 

[Ibrahim]

Did you top up at all during the interval? if you did check, how much oil burn (if any) occurred?

 

[10cent]

Originally Posted By: Ibrahim
Did you top up at all during the interval? if you did check, how much oil burn (if any) occurred?


Nope. I've never had to add any oil and have never noticed the level change on the stick. I check the oil every other weekend or so.

OVERKILL, I looked at the fill hole and I'm sure I can get a decent picture when I get to my camera at my office Saturday. The camera on my phone wasn't up to the task.

 

[OVERKILL]

Originally Posted By: 10cent
Originally Posted By: Ibrahim
Did you top up at all during the interval? if you did check, how much oil burn (if any) occurred?


Nope. I've never had to add any oil and have never noticed the level change on the stick. I check the oil every other weekend or so.

OVERKILL, I looked at the fill hole and I'm sure I can get a decent picture when I get to my camera at my office Saturday. The camera on my phone wasn't up to the task.


Excellent! I look forward to seeing it

 

[Ibrahim]

Hmm... I guess if you like to extend your OCI, you may just have to take your car for a long HWY drive at least once a month! M1 Euro's performance was nothing short of amazing! Thanks for sharing your UOA

 

[10cent]

Updated report with TAN included.

Lousy weather over the last two weekends has deterred me but I will have pictures of the oil fill hole up this week.

 

[Quattro Pete]

Most labs/analysts would condemn an oil with TAN higher than TBN. But looking at the metal numbers, one couldn't tell that any harm has been done. So, is it really a harmful situation that just doesn't show up on a $20 UOA, and if so, what harm exactly is it causing?

Or is it of no concern at all, in which case, why even bother getting the TAN tested?

Diskutieren!

 

[10cent]

Originally Posted By: Quattro Pete
Most labs/analysts would condemn an oil with TAN higher than TBN. But looking at the metal numbers, one couldn't tell that any harm has been done. So, is it really a harmful situation that just doesn't show up on a $20 UOA, and if so, what harm exactly is it causing?

Or is it of no concern at all, in which case, why even bother getting the TAN tested?

Diskutieren!


When I requested the TAN Blackstone actually asked if I was sure I wanted to spend the $10 and indicated that it wouldn't provide much useful information in this situation. It would seem they do not believe the TAN being slightly higher than the TBN to be an issue.

 

[OVERKILL]

Originally Posted By: 10cent
Originally Posted By: Quattro Pete
Most labs/analysts would condemn an oil with TAN higher than TBN. But looking at the metal numbers, one couldn't tell that any harm has been done. So, is it really a harmful situation that just doesn't show up on a $20 UOA, and if so, what harm exactly is it causing?

Or is it of no concern at all, in which case, why even bother getting the TAN tested?

Diskutieren!


When I requested the TAN Blackstone actually asked if I was sure I wanted to spend the $10 and indicated that it wouldn't provide much useful information in this situation. It would seem they do not believe the TAN being slightly higher than the TBN to be an issue.


I think Doug Hillary covers it well in this post:

Originally Posted By: Doug Hillary
Hi,
mechanix - The two number are "in conflict" if you like

The TBN represents the alkalinity and the lubricant's ability to neutralise acid (D2896 or D4739). A high TBN was required with high sulphur levels in fuels. Typically as the TBN is increased the SA level rises - this is undesirable in certain engine families. So Blenders have a problem - new chemicals have somewhat solved this and we see lower levels of TBN in new products. Ideally we need a mid range TBN and a low SA level for most modern engine families

The TBN falls with use and a condemnation point of 1 D4739 or 2 D2896 is used by a number of engine Manufacturers

The TAN measures the build up of acidic contaminants and is a rising number. There may be a TAN limit in some cases and the two do not form a close and predictable ratio in use - or I have never detected it!

With diesel engine UOAs I have always used both - this has been to confirm one to the other. Lab results do vary and people make mistakes

I never set a TAN limit for my engines nor had one set by an engine Manufacturer

The typical levels at OC for me were TAN 6 and TBN 2 (D4739). I have detected many Lab errors over the years with the TBN being inconsistent in decline - this can be detected by movements with the TAN. This is why trending UOAs - especially within similar engine families - is very important

In heavy high speed diesel engines a low TBN was never a lubricant condemnation point for me - it was always soot or iron levels - or both!

 

[badtlc]

I think Terry Dyson also said that TAN being greater than TBN on its own does not mean the oil needs to be changed. Maybe one of the local tribologists can explain why.

 

[10cent]

Originally Posted By: badtlc
I think Terry Dyson also said that TAN being greater than TBN on its own does not mean the oil needs to be changed. Maybe one of the local tribologists can explain why.


This is my personal belief from the information I've read on this site over the years but after seeing so many responses in UOA threads that a TAN higher than TBN is a no-no I figured I'd check mine out.

 

[Quattro Pete]

Yeah, I know that's Blackstone's take on this subject. On the other hand, the lab I use (Wearcheck) uses TBN and TAN in combination to determine whether the condition of the oil is abnormal (not suitable for further use). I'm not saying that one is right and the other is wrong.

The official explanation is that lower TBN-higher TAN situation means that the oil’s ability to neutralize acids has dropped significantly, there is more acids being produced than the oil is capable of neutralizing, and as a result corrosive engine wear will occur. But if there is in fact corrosive engine wear taking place, the particle counts in the UOA don't seem to show it, so how do we know that this corrosive engine wear is really occurring?

Not a question for you... I am just thinking out loud.

 

[ottotheclown]

This is the first TAN # in awhile. So suppose you take it to the popular 10k would TAN be much more?? A uoa with short trips as these of the op should always include the TAN# without you are not getting your money's worth. Makes you wonder about longer oci because you are using syn., with short trips being how you use oil. So I understand from this report a much better oil is showing a increased TAN, yet it seems no wear, but I thought uoa's are not a good indicator of wear, and alittle TAN # higher is nothing to worry about, but it still looks clean?? HUH?? You can assume tha short trips with a very good oil still should dictate no more than 7k. Wonder what 5k # would be??