Originally Posted By: SonofJoe
GTL base oils have very high resistance to oxidation, which is good. They also have a high Viscosity Index and require relatively low levels of VII polymer, which is good. As a result of their high VI, oils made from GTL tend to have relatively low Noack volatility, which is good.
However GTL base oils have very poor innate solvency properties. And there's the dilemma. Because of their high resistance to oxidation, low VII content and low Noack, you shouldn't get a lot of deposit formation with GTL base oils so they should in theory be very 'clean'. However should circumstances be such that you do create even a small amount of chemical 'gunk' in the oil, don't expect the oil to hold it up in solution like a Group I oil might. Rather expect it to plop out somewhere where the engine is relatively cold.
If I was being asked to chose between GTL and PAO, and there was no difference in cost, I would probably opt for the PAO oil only because PAO oils tend to be formulated with a slug of ester base oil to improve seal elastomer compatibility. Ester base oils tend to have both very high solvency and a degree of polarity which makes them ideal for keeping 'gunk' in the oil and off metal surfaces. This is just my personal opinion and not based on fact. Feel free to disagree!
Very informative.
Thanks