I think the tool with more chip clearance on the flutes is the better tool, i.e. more space to hold carbon (I think a drill bit wins). A spiral flute traps more carbon than straight flute, which tends to push the carbon into the pre chamber. When using a reamer, do not fill the flutes completely with grease. You want a thin layer and give space for the carbon. Also do not go in all the way in one shot. Go in a little, take out and wipe off, re-grease, go in a little more, repeat. This will minimize pushing carbon into the pre chamber.

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked