Magnatec is semi-synthetic oil. It's not in the same league as the fully synthetic oils.
The pecking order goes:
1) Fully synthetic. Made from chemical compounds, rather than crude oil. At the microscopic level, think spherical beads, rolling around and lubricating the engine very well. Much better at all temperature ranges. Very good on cold start-up. Low-ish viscosity and a good viscosity range. Reduces hydraulic losses when being pumped around the engine. Last longer. Includes Mobil 1, Castrol Edge, Shell Helix, etc. More expensive, but worth it.
2) Semi-synthetic. A blend of about 30% synthetic and 70% mineral oil.
3) Mineral oil. Millions of years ago changes in the climate caused massive die-offs of small marine plants and animals like plankton. Trillions of their tiny corpses sank to the bottom of the oceans and later got subducted under tectonic plates, where they were subjected to enormous temperature and pressure in an oxygen-starved environment. They slowly turned into kerogen, then into crude oil. We use the fractional distillation process to separate the different viscosities of liquid like naphtha, petrol, parrafin, diesel, marine bunker oil, light machine oil, heavier lubricating oil, grease, bitumen, asphalt, etc. from crude oil. At the microscopic level, think irregular shapes like grains of sand, rather than spheres, lubricating the engine.
Edited by: move up!