I'm not familiar with your particular engine so take whatever I say with a grain of salt. I'm also a relative newbie at doing this. Having said that, there is a good article on the front page of BITOG that was written by Doug Hillary that touches on UOA's and extended drains a bit that you might to read if you haven't already.
Originally Posted By: BorchtWarrior
My after I installed my bypass filter I changed oil and ran it to the same interval as prior to the bypass filter, about 12,000 to 13,000 km. I did this to see if there was an improvement with the bypass setup. I believe there was some improvement but it is hard to quantify.
You mention that it is the second analysis ..... but you only posted one set of numbers correct ?
A big part of the value of UOA's is
trending - how do the numbers from the one, compare to the other ?
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I think the motor was still breaking in prior to the bypass being installed so a drop in wear metals might be the break in issue not better filtering.
Maybe ..... I would guess that is entirely possible - but again I am not familiar with your specific engine. I know when I installed a bypass on my rig I did see significant a drop in wear metals - immediately.
I'm running a Mercedes 2.7L L-5 diesel (MBE600) in a Dodge Sprinter and I don't consider that my motor was truly broken in until around 100K miles - based on "feel" (something that is highly subjective I know) and other factors (decreased oil consumption, increased fuel mileage)
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TO clarify my wear metals right now are the same level as prior to bypass install. And there is about 5000 more km on the oil.
Possibly not enough difference in mileage to be statistically significant .... dunno .....
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My sample interval is not very consistent though. I've taken three samples one at 12992 km(changed oil), 11644 km, and now at 17765km(or 6121km after previous test)
Three ????? ........ where are the rest of the numbers ??? (from the other tests)
Ya gots to look at the trends .....
Having said that, I would think that the data would be easier to think with if you sampled and analyzed at consistent intervals. I'm currently doing so at every 10K miles, trying to use cautious approach until I can establish my maximum reasonable OCI. Once I have that established, I will reduce the number of samples/analyses - probably one at the mid-point of the OCI, say 30K miles (or whatever it ends up being) and one at the end (60K miles ?), at drain. If I end up with a longer OCI than 60K miles (but less than 100K), I may go to three samples/analyses, with one being at drain.
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I would agree that more tests are better until I establish my comfort with an extended OCI.
The more data points you have the better you will be able to trend - I would say that a big part of the value of UOA's are not just
absolute numbers in terms of the wear metals (remember these
accumulate), but the trending of the wear metal data over time, in addition to the other aspects of the oil's condition.
As an example:
"Are wear metals accumulating more rapidly in the last analysis, than they did in the previous one ?"
One other thing - I wouldn't count on being able to get consistent results between different labs - pick one that you feel is good/reliable that you are comfortable with and stick with them.
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What UOA interval would you guys suggest in the short term until my OCI is established? Lets say I decide that I am going to drain at 25,000 km.
I would maintain that you shouldn't "decide to drain" at any particular arbitrary interval - you should sample the oil and let what you see on the analysis determine where the drain interval should be - otherwise, why bother ? Of course what you should really do is whatever you are comfortable with.
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How many UOA's should I take during the next 25,000 km OCI?
I dunno ..... one at the end ?
Seriously, like I have said, my only experience is doing this with my vehicle. Before I added my bypass filter, I was using my vehicle's built-in oil quality sensor (ASSYST) to determine drain intervals. The sensor measures the dielectric properties, or conductance, of the oil as way of determining the quality of the oil - it would generally tell me to change out the oil between 12K+ and 15K+ miles - I believe that it was pretty conservative (with Mercedes offering a 5 year/100K mile warranty on the engine I'd imagine it would have to be) No UOA's were done when I was using this regimen, until just prior to adding the bypass (in order to obtain a reference point of the engine and lube prior to bypass filtration)
I did my first UOA at change out with 14,183 miles on the oil, and 117K on the vehicle, prior to the installation of the bypass filter. I did another UOA at change out (16K on the oil, 133K on the vehicle) on the next oil change, after having installed the bypass at roughly 13K miles into that oil change.
I am now in the process of determining what the maximum reasonable/safe drain interval is for my setup with the oil I am using (M1 0w40 European Car Formula) The first UOA on this oil change was done at 15,707 miles into the (now current) oil change to observe how the oil was doing, as a consequence of having had the bypass on for the entire oil change interval thus far. Wear metals and insolubles (soot) all showed significant decreases.
The next sample was taken at 24,976 miles into the current oil change. The most recent sample was taken at 36,572 miles into the current oil change, and, as of today, I'm now roughly 40K in. I will sample it again at 45K in, and expect to get at least another one or two 10K mile increments in before it starts coming anywhere close to condemnation levels.
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Do TAN and TBN test need to be done every UOA?
Depends ..... how much data do you want to have to evaluate ? More is always better - within economic reason. I did a TBN (for the first time) on the first sample of my current OC at 15,707, as reference for how far the add pack had been depleted at that point and to shed some light on how far it might be possible to go. But I held off on doing the first TAN until I was at 25K miles in - because I figured that the acid level was probably good up to that point (it was), and at that point I was really heading into unknown territory, in terms of how far I was extending.
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What purpose do they serve?
Your in-service oil can have both base and acid properties at the same time.
The TBN or Total Base Number will show you the base level, or basicity (opposite of acidity) of your lubricant. The base components of a lube's additive package serve to neutralize contaminates in the oil that are acidic. The value of the TBN is to ensure that there exists sufficient levels of the base components left in additive package to neutralize any acids that may develop.
The TAN or Total Acid Number shows the overall acidity in the lube, or acid concentration level - it important to understand that acid concentration is different than acid strength. Your oil may have a fairly large concentration of acidity, but if the strength of those acids is at the strength of tea - say an Earl Grey - the corrosive potential is alot different than if it were at the level of say, a 50% solution of sulfuric acid. At least that's my understanding of it.
Using (or graphing) the trend lines for these two items, will give you a decreasing TBN and an increasing TAN - the rate of increase or decrease for both might shed some light on how the lube is holding up. My guess is that the rate of change will not remain constant as the lube ages - it will increase.
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Sorry for all the questions, just want to be careful with my truck but want to extend OCI. Want my cake and eat it too...
Understandable - I'm the same way myself. Finding out how far you can go can be a bit of a torturous exercise.
Like I said, I'm relatively new at this so take what I've said with a grain of salt.
