AVISTAR / INTERNATIONAL DIESEL engines with
Hydraulic Electronic Unit Injectors, used in Ford pickups, vans
and school buses, sometimes suffer drivability problems due to oil
foaming. Leaching of RTV silicone from the oil pan gasket into the
oil causes the foaming. Foamy oil interferes with fuel
injection, which reduces engine power.
The ASTM D 892 Foam Test, Sequences 2 and 4, are
used to evaluate diesel oils on their foaming characteristics
relevant to this engine. Recent testing performed by an
independent lab shows the results below.
According to test results, AMSOIL Synthetic
15W-40 Heavy Duty Diesel and Marine Oil (AME) and AMSOIL Series
2000 Synthetic 5W-30 Heavy Duty Diesel Oil (HDD) are clearly not
prone to foaming or contributory to the foam-caused drivability
problems of the IH engine.
The test also shows AME and HDD dissipate foam
more quickly than Rotella T, a popular diesel oil often
recommended by Ford. Faster foam dissipation means reduced foam
related drivability problems.
You should know that silicone leaching
diminishes with increased engine mileage, and in the meantime the
solution to foam-induced drivability problems, regardless of oil
brand in use, is an oil change.