My bathroom has a single handle faucet that I want to change out,
inside the sink cabinet is 2 shutoff valves coming out to 3/8 outlet (i think compression type) pointing up. It is plumbed with small hard copper lines from the valve up to the faucet.
The faucet clamps by 2 toggle bolt angle anchors. I plan to loosen these first. Then will there be any difficulty undoing the compression fitting from the shut off valves? everything look slightly oxidized
The new faucet will use a 3/8" inlet to 1/2" outlet teflon lined, braided hose up to the faucet.
You may be able to use a little heat to loosen them up if they give you a hard time.
Try not to use a crescent wrench on the brass, tubing wrenches being ideal; or in this case, since you're scrapping the tube anyway, cut the tube and use a 6 point box wrench or socket.