^ I followed your guide pretty much as well with the use of VG diff grease in lieu of green slime and the tamiya shims (0.3mm)
I also sanded the gears slightly - to 3.60mm and 4.55mm exactly.
The VG grease is very smooth with a quite distinct smell to it actually!
No leaks so far!
Word word of caution is the VG grease needs to be used with mineral oil only though.