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Break In

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Old Sep 6, 2015 | 09:20 AM
  #1  
lpresnell's Avatar
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From: Western NC
Year: 2000 & 1997
Model: Grand Cherokee
Engine: 4.0
Default Break In

On Wednesday or Thursday, I hope to start my rebuilt engine for the first time. I just watched a video about Joe Gibbs break in oil. Anyone have any experience with this? It's only good for about 400 miles so it's relatively expensive. It's supposed to help break in the cam, as it has more zinc additive. So is it worth it or just use regular oil? By the way, it is called Driven now.
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Old Sep 6, 2015 | 03:04 PM
  #2  
JPXJMOAB's Avatar
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From: Minnesota
Year: 1999
Model: Cherokee
Engine: 4.0L
Default Break In

In my experience I'd just use regular oil on a break in. I would not want to use any additive, especially during a break in.
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Old Sep 6, 2015 | 03:41 PM
  #3  
dave1123's Avatar
Old fart with a wrench
 
Joined: Nov 2010
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From: Manlius, east of Syracuse, NY
Year: 2000 XJ Sport & WJ Laredo
Model: Grand Cherokee (WJ)
Engine: 4.0L
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The break-in procedures have been a controversial subject since Ford built his first one! There are only 2 areas of major friction to be concerned about, the piston rings and the cam lobes. I've rebuilt many engines in my life and all I ever did was use a moly-d cam lube on assembly and idled the engine to normal temperature before putting any load on it. I haven't seen positive proof that the cam lube does anything special, so you can take that as questionable also.

My Chrysler Hemi was the most highly modified engine I ever built and that overheated in the first 15 minutes of running, at which time I shut it off and let it cool, then restarted and let it idle up to temp again. It was fine after that. I think that was the initial ring break-in. I used a standard 10W-30 oil and drove it normally for about 100 miles before attempting to wind it up. I changed the oil and cut open the filter to see if there was any metal in it. There wasn't, so I figured I had a good one. I took it to the strip after 250 miles, changing the oil before and after. The hardest part for me was trying to drive it NORMALLY for the first 250 miles. When you've got a monster motor under the hood, it's too tempting to stomp on it!

One thing I would suggest though is to disconnect the ignition and crank it over until you've got oil pressure before you fire it. Most of the bearing wear in ANY engine is on start-up before oil pressure comes up. JMHO, but use whatever oil you plan on using for the life of the engine.

Just the musings of a 70-year-old teenager.
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Old Sep 8, 2015 | 07:45 AM
  #4  
bigbadon's Avatar
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Year: 2004
Model: Grand Cherokee
Engine: 2000 4.0
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No need for anything special. If you used assembly lube on everything your golden. If not just spin the oil pump for a minute to circulate oil everywhere.
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Old Sep 8, 2015 | 10:17 AM
  #5  
JPXJMOAB's Avatar
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From: Minnesota
Year: 1999
Model: Cherokee
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Default Break In

You should have primed the oil pump before hand either way.
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Old Sep 8, 2015 | 10:59 AM
  #6  
Fred/N0AZZ's Avatar
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From: Monett, MO.
Year: 1999
Model: Cherokee
Engine: 4.0
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Originally Posted by bigbadon
No need for anything special. If you used assembly lube on everything your golden. If not just spin the oil pump for a minute to circulate oil everywhere.

Yup down through the distributor opening and spin that till I see at least 40 psi. Then close that puppy up and get it on the engine dyno.
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