This truck was running our top, cream-of-the crop CI-4+ diesel oil in his truck: our HDD 5W-30.  This oil is the toughest, longest lasting CI-4+ oil money can buy.  Believe it or not, it actually protects slightly better than our premium 15W-40, it’s that good, while adding the huge benefit of improved fuel mileage to big diesel operators when compared to a 40 weight oil.   A trucker can easily spend $100,000 a year on fuel hauling heavy loads with his rig, so if he can save 3% by switching to our HDD diesel oil that turns into a fat Christmas bonus just like that.  It’s well worth the money for this reason alone. 

This oil was sampled at 15,000 kms.  The report is good and mostly a white sheet still, and the lab confirmed it was suitable for continued use.  The only item of minor concern in my mind is the fuel dilution.  It was not a big deal at this point, but the rate of accumulation is what I would keep my eye on if it were my truck.  (Note: all light duty diesel pickups made by the big three from 2007-2010, and some after that, as well as certain heavy-duty diesel engines have significant fuel dilution issues due to poor emissions equipment implementation and other design or build flaws.  Ask me if you have questions about this.) 

The lab flagged the fuel dilution with green as it was a minor concern at this point, but in another 10,000 kms it could have become more serious if the rate of ingress remained constant.  This oil just barely dipped into the 20 weight range because of the thinning effect of the fuel.  Our partner lab knows the details on this oil and just how good it protects so they only listed this as a minor concern here.  However, because of the harmful effects of cumulative fuel dilution on oil and what this can do to engines, owners should keep track of it if it ever surfaces in a report. 

One main thing the owner of this vehicle could have done to minimize this was to not idle the engine so much.  I happen to know this vehicle is idled excessively, especially in colder weather, and was often used for short drives.  These operating conditions are the prime contributor to the minor fuel dilution here.  This engine (in general) does not have fuel dilution issues like some newer engines do.  Another help would be our “Diesel Injector Clean,” a fuel additive that helps keep injectors clean and atomizing fuel properly.  It also fights acidity in oil and lubricates the fuel system.  When injectors get dirty or partially plugged with dirt or carbon they cannot atomize fuel properly and their spray pattern gets botched.  When that happens fuel can spray the cylinder wall in jets and some will wash down into the sump. 

The rest of the report is good.  The Moly is residual from a previous oil before AMSOIL was used and is a non-issue.  The Magnesium is also residual and leftover from the previous oil, many of which have Mg levels many times higher than what AMSOIL uses: another non-issue.  Overall, this oil was still doing a great job protecting this engine at 15,000 kms, even with minor fuel dilution going on.  There is very little engine wear, and the owner even commented on how well the truck seemed to run while this oil was in it.