Grease is good!
Any grease is good when applied frequently. Due to the load requirements and not being a high speed application the cheap moly based grease will work.
Do remember to unload the spring tension (under deck access cover) to the idler pulley pivot point when greasing it. It tends to neglect the portion of the cavity that requires the grease the most, thus, resulting in pivot bushing wear.
As always; "Grease is cheaper than replacing parts!" Keep up the preventative maintenance and grease away.