Changing a parts CFrame on the Y Axis?

Hey I've asked a lot of questions on CFrame but this answer isn't turning up on the internet. So I have a part that I want to rotate on the global Y axis, not its Euler Angles Y axis or basically, no matter what rotations it x and z axis are at it will turn falt on its Y axis, this is my current script but code but if its x or z are rotated it rotates on an axis that is the y axis of the part rotated. Not sure if this makes sense or not? and there are no errors

part = script.Parent
while wait() do
part.CFrame = part.CFrame * CFrame.Angles(0,1,0)
end

This works but if i rotate the part on its x axis it doesnt rotate flat on the y axis How would I do this?

OK, this works for me. This will create a pre-rotated part and continuously rotate it 10 degrees about the world Y axis once every 1/30th of a second.

local part = Instance.new("Part")
part.Anchored = true
part.Size = Vector3.new(15, 1, 15)
part.Position = Vector3.new(0, 11, -11)
part.Rotation = Vector3.new(45, 45, 0)
part.Parent = workspace

while wait() do
	-- Take the position out of the current CFrame to leave only its rotation
	local currentWorldAxisRotation = part.CFrame - part.Position
	
	-- Get an rotation matrix for the desired rotation
	local additionalWorldAxisRotation = CFrame.Angles(0,math.rad(10),0)
	
	-- Apply the rotation to the part's current position and rotation. additionalWorldAxisRotation MUST be multiplied first
	part.CFrame = CFrame.new(part.Position) * additionalWorldAxisRotation * currentWorldAxisRotation
end