MPG, about 28 city/highway. As far as performance, it didn't seem to matter much as far as brand goes. At least to ye 'ole butt dyno.
According to the link I provided a few posts ago, Lukoil is not TT, nor do they guarantee their fuel quality.
We still have a Getty down the street from us on William Penn hwy. I have used it a few times and it seems to run pretty good on it.

If it works, why change it. As an aside, Getty was bought by Lukoil 9 years ago.
If your RX uses premium, is it 91 or 93? If it's 93, maybe that's why it doesn't like Turkey Hill, which is a 92? If so, maybe the knock sensors are a bit annoyed??