This part of ISO 8178 specifies fuels whose use is recommended for performing the exhaust emission test cycles given in ISO 8178-4.

This part of ISO 8178 is applicable to reciprocating internal combustion engines for mobile, transportable and stationary installations excluding engines for motor vehicles primarily designed for road use. This part of ISO 8178 may be applied to engines used e.g. on earth-moving machines, generating sets and for other applications.

Reference fuels are usually representative of specific commercial fuels but with considerably tighter specifications. Their use is primarily recommended for test bed measurements described in ISO 8178-1.

For measurements typically at site where emissions with commercial fuels, whether listed or not in this part of ISO 8178 are to be determined, uniform analytical data sheets (see clause 5) are recommended for the determination of the fuel properties to be declared with the exhaust emission results.