2000 Chevrolet 2500 - Can I switch to synthetic now?

I put a re manufactured or re built 454 in my Chevy truck, have approximately 4000 miles on it now, can I start using synthetic oil now ? Some people are telling me that I will screw up my engine, synthetic oil will damage or distroy it. How can it hurt any Rings or bearings, re man same as new no? I want to use Mobile one. I have a 2000 K2500 Chevy truck, 454 engine, roller lifter cam engine. What is the truth?

I always have switched over to synthetic at the first oil change at 500 miles, never had a problem, but then I’ve only dealt with 2 rebuilt motors.

I have dealt with bunch of rebuilt engines and all have been run on synthetic from about 5 hours on. Do startup with mineral oil, switch to synthetic at well less than 4000 miles. No problem, switch away!

Agree with the others. What does the company that rebuilt it say? Is there any warranty? Do they have any requirements to meet the warranty?

Of course, the synthetic needs to be the same grade (‘weight’) as the mineral oil.

Depending on motor design, materials used etc, some motors require mineral oil to properly wear in the rings to cylinder walls. Regardless, you are well past that period and can run synthetic if you so desire…