what to make of an oil sample ?

[mudhole]

i am looking at an old cat dozer. the oil was tested, everything was single digits except lead , 18ppm, copper 240 ppm and iron 90 ppm.

my thoughts are, how valid is an oil reading? I imagine it fluctuates depending on when the oil was changed? if it is valid, are those numbers in the range where you would walk away from buying it?

 

[mudhole]

ohh, those above were the engine readings, these are the hydraulic readings : copper 11ppm, iron 11ppm and silicon 10 ppm.

 

[John C.]

A single sample is of very little use for anything other than a catastrophic incident. Wear metals have to be trended over time to mean anything. What you are looking for in a one time sample would be antifreeze in the engine oil or fuel dilution and possibly soot readings. Your stated readings on the engine oil might only be an extended oil change interval or those levels may be normal for that engine. What you are looking for on hydraulic oil is the size and number of particles in the oil. I haven't had to read those in a long time but you should see a three number ISO reading that might show something like 19/16/13. Someone will be able to tell you what you have if you post those readings.

 

[mudhole]

thanks for the quick response, that is what I was thinking as well.

 

[Delmer]

Those are all high in the engine oil. Look at the soot, TBN and oxidation, that will give you a wild guess on the oil life, so if the soot, and oxidation are low, and the remaining TBN is still high, then the oil hasn't been in there long and you have a catastrophic oil test result. If the soot and oxidation are equally high, then it might not be that bad.

the hydraulic oil probably gets changed seldom to none, so the high silicon/dirt is to be expected, and the iron isn't that high considering.

 

[JD955SC]

It’s also important to make sure it’s a valid clean sample

I’ve seen people (well I call them idiots) let the oil run down a dirty final drive and right into the sample bottle. The ideal two methods are a live sample port sample (found on newer equipment usually) and using a clean suction gun and clean tubing to pull a sample directly from the compartment

 

[Nige]

18ppm of lead would make the hairs stand up on the back of my neck, but a lot would depend on knowing how long the oil had been in the engine when the sample was taken.
All I can do is echo what other members have already posted. Between John, JD, & Delmer they've hit pretty much everything.

What model of machine are you looking at.?
Can you post the complete oil analysis for everyone to see.?

 

[mudhole]

it is a d7e, 2700 original hours, and it looks like that is correct, it looks like it is in great shape. the first number is the engine, the second is the hydraulic

SAMPLE ANALYSIS
ENGINE HYDRAULIC
date of analysis Sep 16, 2021 Sep 16, 2021
Silicon 5.34 PPM 11.05 PPM
Tin 0 PPM 0 PPM
Silver 7.25 PPM 0.11 PPM
Aluminum 5.09 PPM 4.01 PPM
Chromium 4.34 PPM 4.37 PPM
Lead 17.78 PPM 0.17 PPM
Copper 240.76 PPM 10.42 PPM
Nickel 0.7 PPM 0.02 PPM
Iron 89.62 PPM 11.54 PPM
Glycol NEG N/A
Water NEG N/A
Fuel <5% N/A

 

[Vetech63]

Copper= bearing
Iron = the engine block where your bearing was/is.

Just an opinion of course

 

[Nige]

A couple of thoughts on seeing the sample results. It appears it was done by an external lab as opposed to a machinery dealer lab. The 2 decimal places in the results (***?) and the lack of interpretation are indicators of that.

Were the samples taken after the machine had been working for a while, or at least after it had been run up to normal operating temperature.? If not their composition could be regarded as somewhat questionable. The importance of correct sample taking methods has already been touched on above.

I don’t know what others think but to me there are too many doubts to put too much store on this analysis.

 

[JD955SC]

A couple of thoughts on seeing the sample results. It appears it was done by an external lab as opposed to a machinery dealer lab. The 2 decimal places in the results (***?) and the lack of interpretation are indicators of that.

Were the samples taken after the machine had been working for a while, or at least after it had been run up to normal operating temperature.? If not their composition could be regarded as somewhat questionable. The importance of correct sample taking methods has already been touched on above.

I don’t know what others think but to me there are too many doubts to put too much store on this analysis.

Another thing Nige has said in the past is never bet the farm on one sample. Take another doing it the right way. You can get a suction pump and bottle kits for a reasonable cost at any Cat dealer and for us at least, the bottle cost includes the lab processing fee and it will have an interpretation summery listing anything unusual, especially anything of concern they detect such as coolant in the engine oil!

 

[Nige]

Another thing Nige has said in the past is never bet the farm on one sample.

I have, but I am far from being alone in that. Oil analysis interpretation is mostly all about looking at trends apart from specific situations such as coolant in the oil or fuel dilution.

 

[Randy88]

As for one sample not being enough history, I'd opt to disagree on that, I sampled a dozer one time and the sample in the engine was so bad, the wear metals so high, on the recommendations they give for recommended drain intervals, that said to change the oil 100 hours sooner next time. The metals score were so high I had to call to ask what they meant, I'd never seen anything like it before [the tech told me to not run the machine, but do an instant tear down and rebuild if I owned it] you could see the color change in the oil itself, the hydraulics were worse. I knew the samples would be bad, but sent them in anyhow just to see exactly how bad they could be.

On another dozer I tried to sample by sucking the oil out, I couldn't get it to suck, so I tried another syringe and finally gave up, got under the dozer and cracked the drain plug, nothing came out, so I used the suction tube and stuck it up into the oil [sludge] and pulled some out that way, looked it over and put the plug back in and walked away from the machine.

When some are so bad, it really only does take one sample to decide NOT to buy a machine.

One of my boys, [who does machining on engines] got an engine in last year, when the drain plug was pulled, nothing came out, he took the pan off and used a shovel to scoop the oil residue out of the pan, then a screw driver, then a scraper and finally a steam cleaner to wash the rest out, then once apart the components went into the cooker which usually only takes once through, this engine it took six cycles through to get the worst off and a lot still had to be hand scraped. Once the oil report came back, nothing was found in the oil, at first everyone though it was vandalized and the owner was trying to get insurance to pay for the engine rebuild due to vandalism, but that didn't happen, turns out you have to provide some receipts the oil was actually changed................even once or twice or regularly and something has to be found in the oil to prove vandalism before insurance will pay. The owner couldn't provide anything or anybody to back his claim the oil was changed regularly so he had to pay it himself.

Strange things happen in life, but before I'd buy anything that has an engine or hydraulics, I'd pull a sample just to see what it shows, or in some cases if a sample can even be taken at all, its a pretty cheap way to get a glimpse of what's going on inside. There are no guarantees any oil sample will give you 100 percent peace of mind, especially with only one sample as a history, but there are times one is more than enough to base walking away on and saying as you walk away, that was money well spent to avoid huge headaches and major cash outlay shortly after purchase.

 

[John C.]

I can usually tell when something is wrong so taking samples on a one time check for a lot of years was wasted money. I only took them to establish a fact of what I put in a report. With the advent of Tier 4 Interim I found that a sample was going to be required for most engines. Firing temperatures were cold producing more soot in the engine oil, fuel pressures are way higher so leaks and fuel dilution became a problem and with exhaust coolers and such I began to see coolant in the samples. So far I haven't seen the same issues with Tier 4 Final engines but time will tell.

Hydraulic systems usually are a different story. A dirty system will show plenty of other problems. Leaking cylinders, hoses and flange seals hint at over heating. Slow cycle times indicate plenty of internal wear. Weak functions imply the same thing. Sometimes I'll take a sample on a system to show that it is very good on an older machine. I'll handle transmissions about the same as hydraulic systems. Hours and stall tests reveal most of what I want to know about wheel loader, dozer and truck transmissions.

Samples on gear boxes like swing and travel final drives are usually a waste of time and money. Few people change those oils when they should and all the samples I've taken in the past show high wear metals. Change the oils and the issues go away.

I still do inspections for some machinery dealers and they require that I sample every compartment on every machine. They pay a premium for it and use those results when negotiating trade values and selling the trade in machines if necessary. With me taking the samples, providing the tubing and suction tool and filling out the paperwork, it costs them around $30 per sample. I take at least a couple of hundred individual oil samples a year.

 

[mudhole]

so there are several for sale, D7es and F's, all with low hours and all look low hours. the earlier oil sampe i posted was for one with 2700 hours, the one i am posting now has 6000 hours, but the oil sample looks much better.


ENGINE HYDRAULIC
date of analysis Sep 16, 2021 Sep 16, 2021
Silicon 3.77 PPM 2.81 PPM
Tin 0 PPM 0 PPM
Silver 0.34 PPM 1.93 PPM
Aluminum 0.91 PPM 1.08 PPM
Chromium 0.23 PPM 0.12 PPM
Lead 5.73 PPM 3.28 PPM
Copper 7.2 PPM 15.04 PPM
Nickel 0.07 PPM 0.02 PPM
Iron 8.88 PPM 4 PPM
Glycol NEG N/A
Water NEG N/A
Fuel <5% N/A

I wonder if the price is similar if it would be better to just go with the one with more hours and then not worry about the oil sample. I just need something that i would put maybe 200-300 hours on a year. I sold my last d7e, because it sat around after i cleared the land I needed it for, that was a mistake.

 

[John C.]

I wouldn't believe the hour meters on either machine. No one spends tens or hundreds of thousands of dollars on a machine and lets it sit. Anything as old as what you are looking at, the hour meter reading really doesn't mean anything other than it has been changed, probably more than once.

 

[Randy88]

You also need to know how many hours are the oil your sampling, if the first one say would have 100 hours on the oil and second would have two hours on it, there is a huge difference. You should also know how many times the oil has been changed recently.

I'd agree with John on the hour meter issue, unless it was owned by the military then someone bought it for personal use, I'd highly doubt the meter is original, that's also not to say it didn't work for decades then someone got it working again. I'd go by looking the machines over top to bottom inside out and determine what condition they are in and make my decision from there. If your not up on what to look for, hire someone or find someone that does and pay them to do the looking for you. Some money spent up front for inspection purposes is money well spent if your really serious about buying one of these machines.

That vintage of machines around here, there were many operations that ran them, brought them in each winter went through them from end to the other and put them back to work again for decades on end before finally updating machines, some had close to 50,000 frame hours on them and they still looked like new and would give decades of service for someone looking to do what your wanting.

Unless you know the owners of those machines personally and they'd give you an honest answer as to the history, go by condition alone, sampling can help but it can also cover up a lot as well. If the right jockey got a hold of those machines, say for example the oil samples were really bad, they'd change oil several times and run them just enough to flush the worst out and only put an hour or two on the machine before someone sampled it again, then dump the oil and repeat till the samples were clean enough to fudge past history and pawn the machine off to someone else.

 

[mudhole]

I dont know the owners, it is an online auction, i am guessing this must be a municipality selling them since there are about 8 of them, all roughly the same year and all d7s. I would agree with you on the hours thing. I think i would prefer to purchase from a municipality than a private owner i dont know, like most government, they dont care about the price they get, its not their money. thanks for all your insights!!!!

 

[Flat Thunder Channel]

I would tend to go old school on an inspection. Operate it a little, check for massive blow by and give the oils a visual / smell / feel test, check the filters (air/oil/fuel). It's not overly scientific, but often will tell you plenty!

PPM values seems like a science experiment to me! I never been much of a chemistry expert. Best of luck on the auction