Echo SRM-3021TES Operator's Manual page 15

Fuel
Fuel supply
Before you start
 Recommended mixture ratio; 50: 1 (2%) for ISO-L-EGD
Standard (ISO 13738), JASO FC,FD grade and ECHO recom-
mended oil.
 Never use two-stroke oil intended for water-cooled engines,
motor-cycle engines.
 Do not mix directly in engine fuel tank.
 Do not add so much fuel that it reaches the mouth of the fuel
tank (A). Keep the fuel within the prescribed level (up to the
shoulder level (B) of the fuel tank).
 Tighten the fuel tank cap securely after refuelling.
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