Max Of 5 Cells Using Offset Reference

Essentially i'm trying to get the max of 5 cells at a time using the 'offset' reference. Here's my erroneous code:

Dim maxCell As Range
For Each maxCell In Range("y9:y150")
If maxCell.Value "" Then

maxCell.Offset(0, 1).Formula = "=max(maxCell.offset(0,-20): maxCell.offset(-5,-20))"

'maxCell.Offset(0, 1).Formula = "=max(maxCell.Offset(-5, -22) : (0, -22))"
End If
Next maxCell

I have two slightly different lines of code here (highlighted in red), one is commented, but i've been changing both to no avail.

I only want this to be triggered when the cell to the left (maxCell) is not empty, hence I use the offset feature. I've tried to use absolute references for the max formula, but then each cell has the same answer.