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The Shimano Altus FC-M311 crank comes pre-greased with four generous drops of grease on one side of the crank's thread (the yellow circles in the image), but it's unclear where it should be used: on the square holes or the threads?
I didn't find anything in the Shimano documentation about this subject and Parktool advice against using grease for a square tapered spindle.
Related: Should square taper cranks be greased before installation?
The dots of grease in question are there to lubricate the bolt shoulder, so that friction there is less of a factor in how much thread preload is achieved for a given torque input. Leave it in place, or borrow some of it to also lubricate the bolt threads.
The bolt threads are the really critical spot to always lubricate thoroughly, but the shoulder is also important, particularly when the parts are new and the bolt and crank need smooshing into their final embrace with each other.
It's always been a standard to grease any metal surface which touches another metal surface.
A massive amount of grease is unnecessary for any contact surface except for ball bearings.
There was some debate about greasing tapered spindles, potentially forcing it too far, but torque specs answered how tight to make it.
I would grease every thread, and make sure to have a rag when the excess squirts out!
