Hi all,

I swapped out my broken 4.0 for a working 4.0, and now, I have my hands on a remanufactured 4.0. Yay me!

When I used to do break-ins on SB Chevys and Fords, I used a break-in oil.

This was 25-30 years ago. I'm wondering about the use of break-in oil on more current engines.

Are they necessary anymore, especially with OHC engines?
Would using the regular conventional 5W30 oil recommended instead?

 

Didn't the company that remanufactured the engine have break-in instruction? I am surprised if they did not. If they did, follow those instructions. If they did not, you should go with new engine break-in instructions from the OEM manufacturer. Break-in oil is not used in new engines. You just run what is recommended for normal use. I am petty sure you should not use synthetic oil during break-in. As I recall, my new engine instructions were, not to run at the same rpm for long periods. Just vary the rpm during the fist few hundred miles. I don't think Ford recommends changing the oil before the normal oil change interval but I like to change it after 1K to 2K miles just make sure the oil does not have excess fine metallic debris floating around in the oil that can be generated during break-in.