I have tried Mona Lisa with oils and since have been trying enamel washes (until now, with enamel thinner). After perusing this thread, I'm thinking my oil washes have been way way too thin**. I look forward to trying oils again with a bit more oil paint in the mix.
**I read somewhere that when mixing an oil paint wash, think 'dirty thinner'. I think I might have taken that to a bit of an exteme. Kind of excited to try it again.