Well, I have some input to add that comes from my personal experiences.
I have over time converted engines from conventional oil to synthetic with very positive results.
I had always done so on a 10% basis....During a scheduled oil change I would substitute 10% of the conventional oil with synthetic oil until the entire system was running with synthetic.
I have NEVER personally had any issues that this article reports to its readers.
The 10% rule every 3,000 miles has NEVER caused issues with my vehicles. All four since have actually ran better, smoother, and cooler.
Take from this article what you wish. But I don't believe it one bit. Convert your motor oil in small increments at a time and there should be no related factors afterwards.
My 1991 Dodge Cummins Diesel Pick-Up Truck is 30% away from being completely converted and has shown NO signs of dismay....It has actually shown improvement through this process.
I don't recommend converting 100% immediately with an older motor. Yes, you could experience gasket leaks (not always) since synthetic oils are thinner than conventional oils.
I also believe that there is NOTHING wrong with continuing to run conventional oil either....A good product that has been proven for longer than any of us have been on this planet.