Synthetic Oils allow you not only a greater interval between changes, but also a greater level of protection because of the lower cold pour points and the much higher temps it can withstand before it breaks down. a 10w30 weight synthetic oil and a 10w30 conventional oil have the same viscosity at room temp, so the synthetic isn't "Thinner". It gets that misnomer because of the superior detergents that are in synthetic oil that really clean the seals of varnish and gum which may result in a short term leak with the first use of synthetic oil. If you have a seal that leaks with synthetic and doesn't go away in short order, guess what, it wasn't long for this world anyway.
When you expose conventional oil to temps above 165 degrees fahrenheit and they begin to break down, AKA oxidize.
Oxidation causes acid formation, sludge, varnish and degrades seals. It clogs oil passages and reduces the lubrication ability of the oil.
Synthetic oils have a higher quality base stock that they are made from in addition to better additives like anti foaming agents, detergents, seal conditioners than conventional oils. That is why they last so much longer, they resist the damaging effects of heat, fuel, combustion contaminants and water much better than conventional oil.
Ever try to pour conventional oil at 0 or below? Put a thermometer in your freezer and see how cold it will go. My deep freeze operates at about -20 fahrenheit. Conventional oil is like cold honey whereas the same 10w30 Mobil One synthetic pours just like it does at room temp. So going into winter, what oil do you want to use on a cold morning? When you run a thinner oil to try and compensate for the colder initial temps, when it reaches operating temperature the oil is too thin.
Run the recommended weight oil, just in synthetic.
In the picture, both oils were heated to the same temperature, which one you think is going to lubricate the best?