VPBR is expensive stuff. It's also hard to get. However, we know what's in it.
Is there anyone making an oil additive to recreate VPBR with cheaper oils?
Just how bad do you think your ring problem is? Sometimes no amount of mechanic in a can (or bottle) can unstick rings to get em to stand proud or worse yet, fix broken rings. (-duh)
You could try several short, 3k mile'ish, drain intervals using a good dino/HDEO with Rislone. Dino's tend to have better solvency due to their higher levels of aromatics. Rislone has an ester (polyol ester IIRC) in it that slowly dissolves sludge. I'd say if you haven't seen an improvement after 2 or 3 oci's, nothing's gonna help. Or maybe your last resort is/are engine flushes at that point.
Good luck 👍
Fwiw.. you can actually double up on the amount of esters by using a 2nd bottle of Rislone for the last 100 miles or so. Of course you'll would need to drain some out of the crankcase to make room for the addtl bottle of Rislone. Also keep in mind that a 2nd bottle will likely have a meaningful effect on 100c viscosity as Rislone is something like a 0w20 - so keep that in mind in choosing your oils viscosity if you intend to double up..
You can visit Rislone's website for more about that but it's pretty much as i just described.