While we're on synthetic and non synthetic, let me mention something non related but it's what shifted me to synthetic about 15 years ago. I had a Brillion seeder with needle bearings in the axles and they were growling so I took things apart for a look. What a mess with bearings needing immediate replacement. Trouble was, I had 30 acres to seed and needed the seeder before the parts would come in.
I cleaned the bearings up and decided to regrease with Mobil One grease just because I had it and I was desperate. Anyway, I was shocked that the growling disappeared and the bearings began to roll again. That should not had happened and I'm convinced the synthetic grease had everything to do with it.
So now I use synthetic oil in everything I can and while I don't use Mobil One grease on a regular basis I do use it for special projects where I need the grease to do Herculean work.
Just my two cents here on what worked for me.