Thank you so much, just ordered! Wil let you know how it works!I've used this before with good results.
Big thank you for such a detailed instruction. Will try it out.Spray straight vinegar on the stains, then press a few layers of toilet paper onto the wet porcelain, and then spritz a little more vinegar onto it.
Let it sit for a few hours, then scrub with a green scotchbrite scrubber.
If stains don’t budge, get the finest grade of automotive wet sanding paper, and buff off the stains with that, while damp.
Car parts stores and even big box stores carry it.
HD has it in the painting dept.
Hard to tell from your pic if the stains are just minerals draining out from the rim holes in the bowl, or if they are from long term mineral build up.
Also try pouring some toilet bowl cleaner down the overflow pipe of the flush valve (flapper).
And let it sit for a few hours before flushing it out.