Synthetic Motor Oil vs Regular Motor Oil

[Mirvin 264]

I used conventional oil in a '99 Mazda B4000 I bought used with 104k miles, changed w/filter every 3000 miles, sold it with 330,000 miles on it and it still ran great. No internal engine issues while I had it. In my '17 RAM, I run Pennzoil Ultra Platinum full synthetic but still change the oil/Mobil 1 filter every 3000 miles. If it works, I stick with it...........

 

[GA 1911]

I use 5w-50 regular oil when breaking in a newly rebuilt vintage engine. Here is a 1965 Mustang but I do the same on all older engines for 10 hours. It helps break-in the engine. Then it's 5w-50 Walmart Mobil 1 synthetic.

On modern trucks and cars, I still use Mobil 1 after finding the proper weight of the oil in the owner's manual. It's 5w-20 on the V-10 tow truck and 5w-50 on a 2019 Mustang GT350 FPC 5.2L:

I have never lost an engine or transmission.