1999 Volvo Penta "WT" Models Workshop Manual, Page 17Get this manual
Gasoline Requirements _ The models covered in this manual are designed for maximum performance with the use of lead-free gasoline with the following minimum or higher octane specification:
Inside the U.S {R+M),i2 (AKI)89 Outside the U.S (RON)93
4.3 Gl, GS, 5.0 GL, and 5.7 GS Models OnlyThe ignition timing will have to be retarded if lower octane fuels, with minimum 86
AKI (90 RON) octane, are usedRefer to 'Timing" in Tune-up SpecificationsWhen ignition timing is retarded, slight decrease in power can be expected
INote Use of gasoline with lower than 89 AKI (93 RON) octane in