Green lid fluid reservior by coolant tank

[davenkay]

What is the green lid fluid reservoir by the coolant tank and fuel filter? It appears to be filled with oil? the lid has a circle with an oid drop and there are squares in a semi-circle.

 

[Sun Baked GL]

Should be the steering pump reservoir.

 

[paul_cat]

Power steering fluid.

 

[car54]

if it needs to be filled, it takes a special fluid. not normal power steering fluid.