I do not believe in any VREF. Only you know the exact value of your aircraft. YOU know how it looks, how it flies, and all the items that are new, rebuilt, old, etc etc. If a VREF SAYS 18K AND YOU HAVE 27K INTO IT,then it's a great deal for someone espesially if yo have great compressions and no oil leaks or usage. TBO's are just a recommendation thats why the FAA does not make them mandatory. I have seen engines go well over 1000 hrs beyond TBO and still be safe and reliable...
