2008 Kobelco Excavator

This is such an impressive page, especially at the end, we hope you can read this one through.  Each report can only show the last 5 samples simultaneously, so there is no room for samples #1 or #2 on this report (but I will still give you the context by summarizing them here).  Subsequent samples stack on top of each other, making it very easy to watch trends as they develop.  Sample #3 is the oldest showing here, #7 the most recent.   Wear numbers reflect parts per million (ppm).  This engine required periodic topping up because the turbo burns small amounts of oil with operation, which the manufacturer states is normal for this engine. 

At sample #1 the owner had the oil analyzed just to have a baseline of sorts.  It was the oil that was in the machine when purchased.  We didn't know what it was, but by the results it was likely a standard petroleum oil.  It was in for about 400 hours and had already thickened to a 50 weight oil even though it had only a tiny amount of soot in the oil.  It could have been used a bit longer, but not for very long.  Once petroleum oil starts tanking it tends to go quick near the end.

At sample #2 the AMSOIL AME 15W-40 Heavy Duty Diesel and Marine oil was sampled for the first time.  The engine wear is very minimal and the oil very good still.  At this point the oil and filter had 411 hours on them.  The copper levels were slightly elevated...see more on this below.  The oil properties themselves were very good still, and the oil was good for much longer service still at this point. 

At sample #3, (top line showing) the oil and filter had a total of 711 hours of use.  You see normal wear amounts reflected in the iron.  The important thing to keep in mind here is that the rate of wear is quite low.  It just looks higher than earlier reports b/c when the oil is in for this long wear metals have more time to accumulate.  The viscosity is still bang on (the mark of an excellent oil) and the TBN is still good at 6.06.  The oil could have been used longer still at this point, safely. 

Note the copper level.  Sometimes there is a short period of adjustment when switching oils because the chemistries differ.  This is normal, and also partly why it’s a good idea to find good oil and just stick with it.  In this engine this manifested itself in a brief spike in copper, which then disappeared after an oil change or two.  I’ve seen this in a number of diesels. 

The oil and filter were both changed at this point (711 hours).  It bears pointing out that the oil filters used by Kobelco for this machine are fairly good glass-mat filters with a 500 hour service rating.  However the filters weren't changed at 500 hours like they should have been, and the soot level was starting to creep up a tiny bit.  It wasn’t bad here at all yet, but you can see the oil viscosity thickening slightly as a result.  Soot is extremely abrasive and wears engine components, thickens oil, hurts fuel mileage and shortens the life of the oil.  Using quality oil & air filters is vital…it’s just as important as using quality oil.  You need to keep them clean and changed on time or you will suffer consequences. 

At sample #4 you see the copper levels stabilizing nicely.  At almost 600 hours the TBN is 6.75 and everything else looks good.  Oil is good for much longer still. 

At sample #5, the same oil and filter have seen almost 1000 hours of use.  Again, the Kobelco oil filters were not changed at the 500 hour mark but remained in service for double their rated lifespan at this point, which is not good.  You can see this reflected in the soot count, which is marked with green for the first time now, and in slightly elevated iron wear rates.  At this point the oil was 2% soot by volume.  As a result the viscosity thickened just enough to creep into the 50 weight class, and the lab flagged it with green to let us know, but it was not a big concern at this point.  If the oil filter had been changed at 500 & 1000 hours the oil would have been in better shape yet and good for much longer still.  As it was, wear rates were still pretty good overall and the TBN was still at 5.47…not new but not bad either considering the situation. 

You begin to see how important filtration is.  Lesser cellulose filters can plug up at 500 hours (I’ve seen that happen on other engines), and that could cause your engine a world of hurt.  A big lesson for us here is: don't neglect to service your filters on time!  No matter what the filter brand: change it when you’re supposed to.  AMSOIL has its own premium long-life filters for most vehicles and some heavy equipment.  They are the best on the market, but they must be changed on time as well.    

Sample #6 looks very good at this point.   Copper content has all but disappeared.  All wear metal counts are very low, viscosity is good and TBN degradation has slowed down and sits very high still at 8.74 with 538 hours on the oil already.  This tells me the engine is getting and staying cleaner after its initial use with the first owner and the switchover to AMSOIL.  The oil filter was changed at this point too, which is good. 

Sample #7 is stunning conclusion.  The same oil has been in this engine now for close to 1800 hours!  The filters had been changed on time all the way through this extended oil drain period, except for the last one, which was in use for almost 800 hours; 300 more than its rated lifespan.  The soot counts have crept up again as a result of this.  This has bumped the viscosity up a bit, but there was another factor involved as well.  This company started topping the oil up near the end of this drain period with our premium 20W-50 diesel oil, which is thicker to begin with.  (The 50 weight oil was intended for an old excavator that burned some oil).  If our 40 weight oil had been used exclusively, the viscosity would likely have been flagged green, like in sample #5. 

All told, things are doing very well in this engine, and the oil is still in descent shape!  The wear counts are very low for how long this oil has been in service, and the TBN is still almost 5.  If the filter had been changed 300 hours earlier things would have looked better still.  Even so, the way the oil was at this last sample shows it was still suitable for continued use, and (especially with another filter change), it could have safely seen well over 2000 hours of service!  That's a lot of saved down-time and oil changes this company didn't have to do for this machine!  These analysis reports are indisputable empirical evidence of just how well AMSOIL's premium oils can protect your engine and how long they can do this.  You can trust the quality and expertise of AMSOIL!