Maintenance and Fluid Information for 2001 GMC W4500 Forward Isuzu 4HE1
For the 2001 GMC W4500 Forward Isuzu 4HE1, you will find 15W-40 and 5W-40 in the engine-oil listings. The matching product listings include Heavy-Duty Synthetic Diesel Oil 15W-40, Heavy-Duty Synthetic Diesel Oil 5W-40, Signature Series Max-Duty Synthetic Diesel Oil 15W-40. Those are product matches, not proof that every listed oil meets every requirement for this engine. Check the manufacturer’s oil specification before choosing one.
What oil viscosity is listed for my 2001 GMC W4500 Forward Isuzu 4HE1?
The engine-oil viscosities listed for this vehicle are 15W-40, 5W-40.
How do I find the correct oil-change interval for my 2001 GMC W4500 Forward Isuzu 4HE1?
Use the manufacturer’s maintenance schedule for this engine and operating conditions. The available application data does not establish an exact oil-change interval.

