Fuel dilution has reduced oil thickness resulting in wear of the bearing and journal.
Kittiwake supply a range of Viscometers for fuel oil viscosity testing.
Info Centre >> Fuel and Lube Oil Technical Manual >> 7. Lube Oil - Test Results >> 7.2 Diesel Engine Oil >> 7.2.2 Viscosity
Diesel Engine Oil Viscosity
The most usual diesel engine oil viscosity grades are SAE 30 and SAE 40 monograde oils or their multigrade equivalents (used in automotive type engines).
A lower viscosity grade may be used to assist in engine starting at low ambient temperatures as it will allow a higher cranking speed for a given starting system power.