I used to run Mobil 1, then Motul 4100 turbolight. Since rebuilding the engine I have gone back to Motul only to find that the rebuilt engine does not have enough oil pressure.
Am now using Pennzoil and it has been a good step. Now some think that Penrite and Penzoil are the same, they are not.
Penrite is S.H.I.T. the only car I have ever even contemplated using Penrite in was a 1982 Sigma that had worn valve guides so it would not blow too much smoke and if it burnt oil it was only shit stuff anyway...
On a side note my engine was rebuilt using chrome moly rings and as such I will not be using full synthetic oil, its too thin, but recommended that you only use Semi-synthetic with stock RB anyway, I have heard this from numerous sources in the State, Aus and Japan. They run full synthetic if they build the car and that is what they should use.
Penrite would not even go in my lawn mower...