In Mercedes Sprinter Maintenance: Engine Oil, I discussed various considerations for choosing a good oil for the Mercedes Sprinter. For starters, the Mobil 1 5W-30 oil that Mercedes uses is a terrible oil, but it is an oil that the EPA has browbeaten Mercedes into using oil for an initially better 1% to 2% fuel economy—at a massive cost over the life of the vehicle in increased wear and even potential engine failure. Use it at your peril but if you do, change it every 3500 miles or so.
Diesel engines are much harder on engine oil than gas engines, and combined with fuel accretion that drops the oil viscosity, a diesel engine can wear badly with a 5W-30 oil. The“30” viscosity is a in the context of the dilutiveand viscosity-robbing effects of fuel accretion—pretty much guaranteed to be bad given that very few Sprinter engines will be broken in properly given the wrong oil used from the get-go.
There are multiple factors to consider: ash content, NOACK value, reduced viscosity in the context of fuel accretion, ability to hande soot load, and how much the oil breaks down due to shear.
On that last point, Amsoil has a good point to make in The shear importance of oil :
If the oil loses viscosity due to shear, it can fail to provide the required level of wear protection. Think of the force transferred through the piston, rod and crank to the thin oil film protecting the bearing. There’s not much room for error.
AMSOIL uses naturally shear-resistant base oils combined with top-tier, shear-stable viscosity improvers. AMSOIL synthetic motor oil withstands extreme heat and shearing forces, exceeding industry standards and outperforming competing brands. In fact, it fights viscosity breakdown 46 percent* better than Mobil 1. It stands up to the devastating effects of high-horsepower, modern engines for maximum protection.
Given that I ran until 18K miles until changing the oil on my brand-new Mercedes Sprinter and that there were some punishing conditions during that time (75 mph freeway, steep hills, 105°F Las Vegas, etc), it’s all but certain that my engine has a lot of premature and totally uncessesary wear. Shame on Mercedes for using inferior and inappropriate oil and (this is even worse) stating a service interval of 20K miles (in 2018, Mercedes cut that in half vs 2017!). In this chart, Mobil 1 Annual Protection 5W 30 is a better and more expensive oil than the Mobil 1 5W30 that Mercedes uses. One has to wonder just how poor regular Mobil 1 5W30 performs.
I don’t Amsoil at present because there is a better oil for my operating conditions ranging from 0°F to 100°F. More about engine oil for Mercedes Sprinter.