Regarding Oil Sampling

[Ted Lambert]

I have been reading past posts as I have been away for the last 13 years and now that the wife and I are back, I thought reading the posts to see whats new and get an Idea what has changed.
I am puzzled with some of the things I have read about oil sampling.
Having worked on fleet heavy equipment of over 300 units in a mechanic and management capacity I seen hundreds of oil samples and I have a real hard time with the fact that people are claiming they had their oil tested and have found that it is good for x# of miles.
In my experience I have only seen samples that list Contaminants or the viscosity of the oil but only as compared to the original weight such as 5w/30.
I have never seen anything on the additives as they do break down. I believe it makes no difference how clean the oil is the additives may have broken down and the protection is no longer there. There are a lot of conditions where oils just don't get dirty. I would like to know how they predict the oil is still OK.

[Ray,IN]

I've wondered just how much information the lab could glean at $30 per sample.

[Ted Lambert]

Yes Ron I agree. Sampling is great but there are some fundamental reasons for it.
They are a great tool to tell you what potential problems you may be having before you have a catastrophic failure.
If people are sampling their oil I hope they are getting a professional interpretation of what it is saying.
There are too many fly by night labs around.
The key is find a good lab and don't depend on a written report with no verbal explanation unless you have the experience to read the report.
I am able to determine from a sample, problems with the engine or transmission or differential, but I have never been able to tell if the oil is still OK.
My thoughts are if a person wants to push there service times because a sample looks good, it may be risky.
I gauge my services on three things.
TIME
SEVERITY OF CONDITIONS DRIVEN
MILEAGE
Recommended service intervals are based on average driving conditions.
Mountain driving in extreme heat is a lot different.
There is no hard and fast rule when it comes to servicing. Oil is the cheapest thing in the RV.

[Gary RVRoamer]

Good question, and I don't think the answer is simple either.

For sure, all that you can really know is that the sample is not contaminated with any of the things they analyze for. I'm willing to take it on faith that the analysis is complete enough to spot potential problems, but seldom have I seen a discussion of additive life. On the other hand, I don't see any information that shows that additives do not have a fairly lengthy life, even in regular use. However, putting some bounds on how long the additives remain effective in moderate, average or extreme usage conditions seems like a necessary condition before yu can estimate that the oil is "still ok". I note that Amsoil, a brand often used to extend change intervals, only claims a service life of 10,000 miles for their 5W30 synthetic oil. They state it may be longer, but give no estimates. So it would seem that one should not attempt to extend Amsoil beyond 10,000 miles, regardless of test results? See Service Life topic at http://www.amsoil.com/shop/by-produc...ont%2fxlf.aspx

Oil additives do several things, and some of them probably can be evaluated via sample testing. For example, viscosity modifiers are one additive and viscosity is one of the things usually reported, though not in terms most of us understand (it doesn't say "10W30", for example). But what about additives for lubricity, friction, corrosion, foaming, etc.? I don't see those factors.

I also don't see any information that is generally available that would tell me how long I can expect the additives in my oil to last. If I knew, for example, that the additives were probably good for 50,000 miles in average conditions, then I could perhaps judge that I'm ok at 25,000 miles as long as there has been no contamination. But where is the data that would let me conclude that?

I don't attempt to extend oil change intervals - I just don't see enough to be gained by it to take the risk. I do, however, do analysis on my synthetic transmission fluid (Allison Transynd), because I do feel that its hydraulic properties remain good as long as it isn't contaminated. I also replace transmission filters on the recommended schedule. But maybe I'm being naive there as well?

[Jwar]

Narampa, I had the same position as you did. We had 200 units from lowboys to all types of heavy equipment.

I was not too worried about the additives breaking down as we serviced to the recomended requirments of the Mfg. We used a good brand of oil and never mixed with any other brand of lubrication.

Oil samples can and was very benificial, however we found that it took three samples to get a good track record for later comparisons of any unit.

Being its elevated in parts per million its easy to catch a dribbling injector,(soot) or an air intake sucton leak between the manafold and air cleaner, the start of iron, crome, babbit, or other combinations of wear metals which will lead to heavey repairs later on. I also relied on the sample results for rebuilding or turning units before repairs would have to be made. We used the sample results for preventive maintainance issues, not for additive breakdown other then the viscosity thinning due to internal fuel leakage.

Perhaps Im old school, as I feel if I have to add an additive to engine oil, Im not using a high quality oil in the first place. An additive problem can arise if two different brands of oil are mixed, as the additive packages of some different brands do not work well togather.

However in anser to your question to additive breakdown, could see in combinations of elevated metals from the report, with excessive hours/miles on the unit.

John

[Sky_Boss]

Even if one doesn't want to use the info to extend the life of the fluids, the info on fluid contamination can help track and suggest sources for that contamination. I think of it as being similar to an overall health check. Sometimes routine blood tests can reveal a condition that is in need of treatment before it becomes more serious.

[FormerBoater]

This why it is important for a meaningful oil analysis to include a TBN analysis.

From Bob the Oil Guy

"The TBN (Total Base Number) is a lubricant’s reserve alkalinity measured in milligrams of potassium hydroxide, or calcium sulfonate per gram of oil. In more simple terms it is the amount of active additives remaining. This number is important because combustion byproducts tend to form acidic compounds and the TBN is the acid-neutralizing capacity of the lubricant. The TBN does not decrease linearly with the time it has been in use."

DaveS
1998 American Eagle 40EVS

[charlie 62]

I drove truck for a company that changed oil (synthetic) every 45000 miles. They also had a test fleet( Detroit ) that changed oil at 90000 . They still got a million miles with testing of oil samples.

[Ted Lambert]

You fellows are so right. I wish i could find the post where the guy said he had his sample come back and it said his oil was good for another 5000 miles???????????
I agree samples are to benchmark and one sample will really not tell much as it takes a few to establish trends.
Thanks for posting the technical side of what I already knew, I am retired and a bit lazy about typing.
It is so nice to read intelligent remarks from obviously very smart and educated people on this question of mine.
My hats off to you all that have replied.
One last thought if I ran a Cummins I would have turbine filters or cyclones as we used to call them. But that's another story.

[Mr_D]

Originally Posted by narampa

You fellows are so right. I wish i could find the post where the guy said he had his sample come back and it said his oil was good for another 5000 miles???????????

Maybe that was mine. I still have the email from JG Lubricants that says that if you're interested.
JG Lubricants is run by a retired Allison fluids engineer who wrote the specs and did testing on TranSynd for Allison so I trust their opinion.

[sc3283]

I change it when recommended or sooner and don't worry about some sampling or it's results. Failure can occur at any given time. I SURE don't sweat about oil samples. Life is too d*mn short to be worrying about "what ifs". All these threads make it appear many with RVs are planning failure with their engines. These diesel engines are built to go how many miles? and how many miles do we RV'rs put on these engines? Too many times we read of failures on here, that are caused by hack mechanics or poor maintenance..Why not just have repairs done by competent mechanics and do them as or before scheduled by the manufacture?

[Mr_D]

Originally Posted by sc3283

Why not just have repairs done by competent mechanics and do them as or before scheduled by the manufacture?

Because some failures, like abnormal bearing wear, will show up in a sample long before a failure happens.

[sc3283]

mr D...yes true but this occurs in what..less than 1% of RV engines?
It is what ever makes the owners comfortable..I personally don't do it, haven't ever seen any need for it and won't do it..even in my 7000+ rpm race engines. Proper maintenance is KEY