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Hey, everyone! I’m in the final days of waiting for parts before I perform an engine rebuild. I own a 2007 Honda Civic Si. I have replaced the engine block, the crankshaft, one of the pistons, the camshafts, all of the VTEC components, and much, much more. I have read the Hayne’s manual break-in procedure so many times I’ve memorized it. I am having a friend, who has rebuilt dozens of engines before, help me rebuild my engine because I’ve never rebuilt an engine before. He insists that I ignore the manual’s break-in procedure and instead “treat it like a $2 wh*re the first 1,000 miles, then change the oil.” When I asked him why I should be so rough on it right after a rebuild, he said “because if you do it that way, the piston rings will seat one way or another.” While I trust his experience more than my intuition, he is very rough around the edges and insists on doing things a certain way, even if that doesn’t seem to be the best way to go about it. What are your thoughts on this?

 
Rep Power: 126

Never heard of that method before.

I’d personally take the more cautious approach, also because I’d be a bit paranoid.

 
Rep Power: 367

most applies to older engines, like pre-90's
newer engines suffers less, but being more careful in the initial miles is good. Check oil at 500-600 miles

https://www.motorcyclistonline.com/b...break-in-myth/
https://www.enginelabs.com/news/disp...mance-academy/

 
Rep Power: 224

I've heard with new rings you want to load them as soon as possible to help them seat. Avoid a constant idle speed while it's warming up then do some 3rd gear pulls from like 2k up to redline, then leave it in gear and coast back down to 2k. Do that a handful of times and the rings should be fully seated. I also read you should use straight 30 weight oil for break-in (SAE 30, not 5w-30). Others said just use conventional 5w-30, just don't use synthetic. That's what I usually found for rings anyways, not for everything else. This is what I did with my new rings and it did not work. However, I think this was mostly caused by me not getting the pistons fully clean before new rings were installed.

It seems half the time people say run it hard, and half the time they say keep the RPMs down. I think people try one way and it works so they keep with it.

 
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Thank you for the advice! The manual says to accelerate from 30 mph to 50 mph and back 10-12 times, so I’ll just do 2k rpm to like 5.5k rpm and back in 3rd gear to load the rings. I will use conventional 5w-30, because it’s starting to get cold in the mornings, but should I add break-in additive to the oil?

 
Rep Power: 367

the reason to use mineral oil is explained in one of the links.
you will need to change the oil in no time also

 
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Okay, is SAE 30 mineral oil?

 
Rep Power: 367

just look for oil that does not say synthetic...

 
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Got it. Thank you!