I've tried lots of different polishs and waxes on my gm and without a doubt the best has been clearkote vanilla moose wax hand glaze, despite the title its a polish and its easy on easy off, zaino z2 and z5 are good but for value clearkote is better imo
SNOWFOAM
With one coat of clearkote
also it pays to buy a good shampoo like poorboys super slick and suds or chemical guys, these will not remove the polish
gm is not the rewarding colour to polish i will admit