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Old timer's break-in oil advice saved my Cummins rebuild
Guy named Hank at the parts counter told me to run Rotella 15W-40 with a bottle of ZDDP for the first 500 miles. Ignored him, used synthetic right away, and ended up wiping a cam lobe at 300 miles on the dot. Anyone else learn that lesson the hard way?
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ward.jamie23d ago
Tbh Hank was right. That ZDDP is mandatory for flat tappet cams during break in, synthetics are too slippery and won't let the rings seat either.
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the_paul13d ago
Man tell me about it... I killed a perfectly good 350 rebuild my first time because I thought modern oil would be fine. That noise when a lobe starts going flat is just gut wrenching, like the engine is crying for help. Now I won't even start a fresh build without a bottle of that zinc additive mixed in the break in oil, just too many horror stories out there. And yeah synthetics are way too slick for rings to grab during that first fire up, they need some friction to actually mate up right. Learned that one the expensive way too...
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finley_price2423d ago
Oh man, @ward.jamie is bringing back bad memories of my first cam swap where I thought modern oil would work fine. Learned that lesson the hard way when the lifter started clacking like a angry sewing machine. Now I just dump the good stuff in and pray the thing doesn't wipe a lobe.
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