# Break-in oil for rebuilt engine



## gtoearl (Dec 21, 2009)

How about break in oil for a newly rebuilt 389..... Heard that a non-detergent oil is the as to go.... how about the weight....10-30 or straight 30 weight. thanks in advance for the help...


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## BearGFR (Aug 25, 2008)

I like Joe Gibbs break in oil. To tell the truth though, the procedure is probably as important as the type of oil you use -especially with a flat tappet (non roller) cam. For those, make sure you use an oil that has plenty of ZDDP (or add it yourself) and DO NOT allow the engine to idle or run below 2000 rpm during the first 20 minutes of running on that critical first start up after being assembled.

Bear


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## geeteeohguy (Feb 2, 2008)

Run what grade you intend to run (10w30) and make sure it is a high ZDDP oil or you have the additive. No need to hunt down non-detergent oil for the break-in. You are going to dump it after the 20-30 cam run-in anyhow. What Mr. Bear says applies, though: NO idling at all allowed for the first 20-30 minutes. If something goes wrong, shut it off. Recommend having a box fan in front of the car and a fire extinguisher handy. Also a water hose or distilled water to top off the radiator as it burps. After the cam break-in, dump the oil and filter, refill with fresh oil, and good to go for the first 500 miles. I would never run the engine on the same oil I broke the cam in on....I like mine to last. Good luck.


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## Colorado67GTO (Sep 11, 2014)

I recently got my engine back from my machine shop and he told me to make sure to use oil with zinc in it. I had told him (thanks to information in this forum) that I had already read about making sure I used zinc-based break-in oil for break-in. Then he said something that surprised me. He said I should use the zinc based oil continuously, not just at break-in.

Thoughts?


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## chuckha62 (Apr 5, 2010)

Colorado67GTO said:


> I recently got my engine back from my machine shop and he told me to make sure to use oil with zinc in it. I had told him (thanks to information in this forum) that I had already read about making sure I used zinc-based break-in oil for break-in. Then he said something that surprised me. He said I should use the zinc based oil continuously, not just at break-in.
> 
> Thoughts?


Absolutely! I run Rotella and add zinc additive with every oil change.


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