Wet sleeve cylinder pitting and pinhole formation question

We are still in the inspection phase of possibly purchasing an 04' Mountain Aire with a Cummins ISL 400hp motor with 71k miles. So far we've only received the coolant analysis tests. The tests show that the engine coolant was in poor condition though I need to speak to a tech to determine exactly what the results mean.
On a 0-4 scale with 4 being critical, the overall score was 3. The following are all the abnormal results. Color- cloudy dark yellow. Basic testing: 7.4 ph, Nitrate ppm - 295-Strip, SCA level 0.6. Corrosion metals: Copper 13ppm. Corrosion Inhibitors: Molybdenum 76ppm. Everything else was within normal levels.

I've read about how important it is to maintain the coolant condition and SCAs in diesel engines with wet cylinder sleeves due to the possibility of pitting to the cylinder sleeves from cavitation due to poor coolant which could lead to pinhole formation. Don't know if this is true, but I was told by a service manager that Cat motors were more prone to the pitting than Cummins.

Am I being unduly concerned about the condition of the coolant which might have the potential to cause severe failure?
Of the repair/maintenance invoices I've received so far, none show radiator/coolant maintenance so I'm guessing there's a good chance the coolant is the original factory coolant. Also, the engine oil was changed a day or two before I arrived to obtain the samples and the old oil wasn't saved.

This will be our first motorhome purchase and this particular coach has several features that we really like but after not having a chance to test the old oil then receiving the poor coolant tests results we are seriously questioning going forward.  Tomorrow I plan on calling Newmar, Cummins, and speaking to the analysis testing tech.
I would like to hear from anyone that has dealt with this same issue or know of someone who has. Your input would be appreciated.

For what its worth, I inquired from a close friend whom owns and operates a large diesel shop, that same question. Answer: don,t even sweat it, my C8.3 Cummins has 91K on the clock and according to him he has only seen the problem in very high mileage engines (500K and up) being used in trucking "over the road" in heavily loaded conditions. I check mine each six months and it always is dead center of all tests.>>>Dan

It is very common for dealers to drop and change the engine oil as that is the cheapest thing they can do and still say they "serviced" the rig. You don't say if this is a dealer or private party?
You are also correct that coolant maintenance is very important for diesels, much more so than gas engines. That said, no tech can tell you what the inside of that block looks like without tearing it down, that is not how an analysis works, it only tells you the current condition of the sample you took. It is a tool used to help in the diagnosis, it is not a final answer. It is very possible you could end up with some electrolysis from it, or you might not experience any trouble if you service it correctly by flushing and installing ELC. I would not say Cat motors were more prone as every engine will have problems at different intervals if they are ignored. The Cat 3126 which is most common in Rv's and fleet trks does not have wet liners like the Cummins, only the larger Cat engines, as an FYI.
The bottom line is if the coolant was overlooked what else has been skipped? Coolant needs changing every 2 yrs or so and is very common (except ELC). I would be very skeptical of this rig being used and ignored unless I find something to prove otherwise like other maint records etc. How is the rest of rig maintained? What about the genset or trans? Their should be many other rigs for sale for you to look at if you're not comfortable with this one. It is cheaper to move on or at least protect your investment in other ways if possible. Good luck with it.

Obviously this coach is due for a coolant change, but I don't know how to accurately answer the question about possible damage from poor maintenance. It may be that SCA levels were maintained even though the coolant was not, i.e. use of a coolant "filter" (actually a slow-release additive package) or maybe adding concentrated SCA from time to time. But even if neither was ever done, it is difficult to predict whether there was damage in a low mileage diesel. Since the current 0.6 SCA level is low but not zero, we can conclude there was some protection and it probably has had at least occasional SCA-related service. The expert opinions I have read indicate that a target level of 1.5-3.0 is good, but I've never seen an estimate that tries to assess the probability of damage from running at 0.6 (or whatever) for some number of miles. Cummins engineers probably have such data, but it doesn't seem to be public.

utahclaimjumper, Mavarick, & Gary.  You have all made good points for me to mull over. The rig is being sold privately. Today I spoke to one of the analysis techs, a Cummins tech, and a Spartan chassis tech. Each one had information I didn't know and gave their opinions, but in the end as I had suspected, they wouldn't or couldn't give a definitive answer has to what damage if any might have been done to the engine which is understandable. I've read in several places where conventional coolant should to be changed every 2 years but seems to contradict Cummins (34 page) service bulletin 3666132-07, published 7/29/13. The person or persons who complied this bulletin are/were way above my pay grade. After trying to read the bulletin and reading what I can find on the net, I at the point of flipping a coin or burying my head in some sand.

Summary of Recommendations
Cummins Inc. cooling system general recommendations are listed below. These recommendations apply to both Standard Service Intervals and Extended Service Intervals. See Section 2 or 3 for complete instructions.
-Fill up and top off cooling systems with a fully formulated antifreeze/coolant meeting Cummins Engineering Standard 14603.  
-Replace the coolant filter(s) at every recommended coolant filter change interval.  
-Add liquid supplemental coolant additive (SCA) at each filter change as necessary or add liquid Extender per the coolant supplier's recommendations.  
-Test coolant at least twice per year for liner-pitting protection (nitrite and molybdate levels).  
-Test coolant for replacement limits every 240,000 km [150,000 mi ], 4000 hours, or once per year, whichever occurs first.  
-Replace coolant ONLY if replacement limits have been exceeded.

The bulletin shows to CHANGE the coolant ONLY if it exceeds the coolant replacement limits.
Table 3 - Coolant Replacement Limits
Contaminant Allowable Level
-Sulfate (SO4)  1500 ppm,
-maximum Chloride (Cl) Fluoride, Bromide 200 ppm,
-maximum Oil or fuel contamination Coolant must not contain oil or fuel pH 6.5, minimum (See Note 1) 
-Grease, solder bloom, silica gel, rust, or scaling Coolant must be free of these contaminants

The minimum pH for a replacement limit can vary according to the product. Consult the product manufacturer for the pH limit. A pH less than 6.5 is always unacceptable. For Fleetguard? ES? Compleat? coolant, the coolant must be replaced if the pH is below 7.5 pH. 
Bromide is typically a contaminant from radiator flux and fluoride is a contaminant from brazing flux. Both bromide and fluoride are corrosive especially to aluminum parts.
If the coolant does not meet the replacement limits of sulfate, chloride, or pH, it must be drained and replaced with new coolant meeting Cummins Engineering Standard 14603. However, if the coolant is contaminated with oil, fuel, grease, solder bloom, silica gel, rust, or scaling, the system must be drained, cleaned, and refilled. See Section 11 for details on cleaning the cooling system.

If I liked everything else about the coach, I would probably buy it, change the coolant and maintain it in the future.

Don't know about Spartan, but Freightliner says to change coolant every 100k miles or 5 years, with SCA checked every 6 months. Even that is pretty conservative for typical RV use, in my opinion.  I changed the coolant in my 2004 Freightliner ISL after 8 years even though it was still fine. I put a new coolant "filter" in every year (but I missed a couple times) and that seems to handle the SCA needs. I have 72k miles on it now.

Look, try not to make it any tougher than it needs to be. With the research you have already done you have proved you are not about to stick your head in the sand, feeling good about your decision is what really counts.
Standard practice for most diesel engines is to change regular coolant every 2 yrs. and ELC with extender every 6.  If you test and you know what to look for you can extend it out a bit but common sense always prevails.
Have we ever let an engine go longer than it should have regarding coolant, sure, but that still means nothing regarding your engine because you don't know the actual history.
You can mull over 20 different tech bulletins and they still will not tell you more about the condition of that rv than what you can see by looking at it.
After inspecting the rig you already have a feeling of how well it was taking care of. If they simply did not do a very good job with the coolant and every other aspect looks real good, including the price, than I also would probably go with it. If I see other things in the rig that show a lack of maintenance then I know they really didn't do a good job of taking care of it and I would walk.
When helping others with past purchases the one common item I seem to see is people get tired of looking and have a tendency to talk themselves into a purchase. I think as long as you use good judgment here based on what you see, you will be fine.

Thanks guys, very good points.

Think about it from the  sellers point of view. Do you get all the service done on a car you are trading in?  It shows to have some SCAs but below the required. If you by it just do the basic maintenance so you have a base line. That is what I did. Now I know the maintenance is done and when it is due.
Bill