If by oval they mean the nuts with the dimples that distort the threads I'd recommend against them as the distortion will damage the threads on the bolt or stud.
What I did is this: I left the original nuts on and bought a set of thin jam nuts from Ace Hardware for about $2 and installed these on top of the existing nuts and tightened them against them. There was enough thread on the studs to thread the jam nuts on fully. This way no thread distortion and easily removable.