Over here I use Castrol High Temperature Bearing grease, it's blue colored.
You know, a lot of the carry on about greasing is BS!
Think about this, how often do you grease the front wheel bearings of you car? Probably never, only when the bearing wears out.
SET up 1/ Many modern bearings are sealed, yet have grease holes so people can pump more of the stuff in, but the grease cant get out ... and then there's more bearing failures ... and ironically the owner who's been through this makes darn sure it doesn't happen again and pumps more grease more often .... another bearing craps it ... oh darn bearings are junk, I look after them so well!
Set up 2/ Or the bearings may not be sealed but they are enclosed in a sealed unit somehow. What happens here is the grease gets out of the bearing but not the housing. But over a short period of time the grease that's escaping from the bearing can't as there's a wall of grease. Continual pumping of grease pressurizes the housing's seals' and breaks them.
Set up 3/ Or worse still, and this is true, the grease track only goes into the bearing housing and not into the bearing ... and if you think that a spinning bearing sucks grease in and not spit it out then you need a shrink.
So, it pays to know what your set up is, and I haven't greased my Dosko's bearings for over a year and they're fine, the previous year I went through 3 sets. They're sealed bearings and by pressurizing the seals with an overflow of grease you blow them, then crap can and will get in.
On my Kanga stump grinder there is
no grease nipples. The older models had them but guess what, it's set up 3, a waste of time. You pack the bearings with grease on installation and forget about them till they're blown.
Cutter wheel RPM on a RG50 or RG 85, I bet it's around 1400rpm, figure out what your car is doing, wont be much different.