M1, 5W-30 EP. It is an AN based oil, holds up perfectly to turbocharger's heat and is commonly available at Walmart. Change regularly. Either HPL or Ams will be great choices too. Keep in mind that viscosity matters more for wear than does oil choice. In fact in test after test, oil brand is shown not to matter with regard to wear.
Carbon, varnish, piston ring sticking and turbocharger lifespan are all affected by oil brand and choice. But with regard to wear, it does not matter much, if at all.
FYI, An HTHS of 3.8 (often rounded up to 4.0) is the point at which an increase in an oil's viscosity reaches a point of diminishing returns (higher produces no significant reduction) with regard to wear rate. In most normal cases. For some race car and air cooled engines running 300 degree oil temperatures, then an HTHS of above 4.5 is a good idea.