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2012 Mustang GTCS/Manual Cobra Jet Setup
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Discussion Starter · #1 ·
i have a 5.0l Coyote that is having a low compression of 95-125. The wet test brought the 95 up to 105.It is burning 1qt every 200miles. The engine has a little over 1000 miles on it at this time 9 Jan 21. The person i bought it from says the rings were seated when i bought it, putting in Full Synthetic before i picked it up at 450miles on the engine. While driving i do get blue smoke that seems to pool up as i engine break and come out with acceleration. I have checked the Coolant for any oil there is none. When i open the oil cap after a drive i do get blow by. I am being told i need to go in and replace the rings but i am also being told to just keep driving it in hopes the rings where not seated in the first place and will take longer due to the full synthetic being put in the engine before being seated in.

The Rings where hand filed for Boost on forged Mahle Pistons, Callies Rods, and Ford Racing Crank.
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I will agree with above...... although "dino" oil hasn't existed for 20+ years, what is termed as "conventional oil" or "break-in Oil" would be the 1st choice. With conventional oil, rings will need about 1000 miles to get "seated" but, if the ring gaps were actually set for "boosted' spec, the gaps will be much larger. It is not unusual to see "new" hand-built engines use oil for up to a thousand miles or so or until break-in has been achieved, the extra-large gap could also explain the blue smoke as well.

At this point I would definitely drop the oil/filter, use a boroscope type device (cell phone adapters would great) to look inside the cylinders to check for the cross-hatch and if both the dry and leakdown cylinder test are about 10% of each cylinder, it's just a break-in issue IMHO.

I will say this.... I have seen engines with 10k miles on them running full syn oil that never achieved breakin
 

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2012 Mustang GTCS/Manual Cobra Jet Setup
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Discussion Starter · #5 ·
Thank you for the info i did put conventional oil back in around 700miles i did not swap the filter to i can knock that out as well. I will get myself a Borescope and see what i can find.
 

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2014 GT, 1967 Fairlane GTA
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The guy that you bought it from almost certainly knew something was wrong which is why he sold it. That's a LOT of oil consumption. It would appear that he also lied if he said the rings were seated or he just left out the truth that the engine had a problem.
Is this engine in fact supercharged/turbocharged now or is it just rebuilt/set up for it in the future?
95-125 isn't even near within 10% like it should be but since the ring gaps are supposedly bigger because it's for a boosted spec that would help explain it assuming the rest of the engine was rebuilt correctly. Maybe they "hand filed" the rings a little too much. Who rebuilt this engine, the owner or a shop?
All that oil burning might ruin the cats. I would buy a cat cleaner to put in the gas tank to try to prevent that.
 

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2012 Mustang GTCS/Manual Cobra Jet Setup
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Discussion Starter · #7 ·
The Engine was rebuilt due to a knock. They used a new block and built it for the future. The Engine was rebuilt by the Owner and his dad who were taught by the Owners grandfather who owned an Engine shop. I will pick up the Cat Cleaner and add it to the next fuel up.
 

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2012 Mustang GTCS/Manual Cobra Jet Setup
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Discussion Starter · #9 · (Edited)
i am using 5w-20 conventional

While out driving last week from work the Oil pressure sensor was dropping to 0 while idling and would go up with the RPMS. I got it home replaced the sensor and got a tester for the oil pressure. At 185 degrees ferinheight at idle the car sits at 10-15 PSI, at 2500 RPM it goes to 60-70psi when i went up to 5000RPMs the Psi jumped to 80 psi but on its way back down, at idle the psi dropped to 0psi for 2-4 seconds and then went back to 10-15psi. The engine has less than 1500miles. We are thinking it's the pressure release valve sticking open but are not sure what is going on. The Piston rings have not fully seated yet. The engine is running 5w20 and is not low on Oil.
 
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