Most synthetic oils today have a base in them that are produced by only a very few companies, from what I understand. Which would mean most of the synthetics are about the same except for the additives that every company adds to them with their name on the product. So a Amazon or Walmart brand oil has basically the same base as a Mobile 1 or Castor oil would have with different wear additives from what I have seen explained. So you should be good to use any brand you want and be fine. In years past with mostly conventional oil was the most common except for Amsoil that was very expensive when running a farming fleet with machines, tractors and trucks. In the 90s I used a blend of synthetic and conventional with no issues in my personal vehicles, because sythetic oil was so expensive. Todays vehicles I only run factory recommended oils and fluids and replace them when recommended. I do have an older 1992 305 I received in a trade with 75K miles on it, no issues except it was a 305 in a haft ton truck and he took pottery room Idaho to Arizona every year, the hills were brutal, so I installed a Summit 383 in 2000 with a chipped ECM for state emissions and he was very happy. Borescoping the 305 that he used Mobil 1 when new, had a brownish film that you get from not changing the oil often enough, the oil can go 15 to 20K no problem but the filters can't. The filters should be replaced (I think every 4 to 5K miles) My 1972 Chevy 402 I'm trying 5w-30 synthetic because of the billet roller camshaft with a Melionized distributor gear and shouldn't use a high volume oil pump to not overload the cam gear, and using a 0ne piece rubber type pan gasket because the older cork gaskets leak with synthetics. So far all is good.