Oil and Maintenance Guide for 2003 Honda TRX400EX 397
Before You Service the Engine
For the 2003 Honda TRX400EX 397, planning an engine service involves checking the correct lubricant application and following the proper refill procedure. Before removing the drain plug, identify the correct refill and level-check procedure; a published capacity does not necessarily equal the amount needed after a routine drain.
What kind of oil does a 2003 Honda TRX400EX 397 take?
The engine-oil viscosity shown for this model is 10W-40. The available oil-product listings include 10W-40 Synthetic ATV/UTV Engine Oil, Formula 4-Stroke Power Sports Synthetic Motor Oil. For a service, choose oil that meets the engine’s actual application requirements, not just a product name.
Does synthetic oil automatically mean an ATV can go longer between oil changes?
No. The oil-change interval also depends on the engine, operating conditions, and manufacturer requirements. A synthetic product listing does not establish a longer service interval for this particular model.
