How I made my oil-burning, pinging, clattering 3.8 purr like a kitten.
12-07-2012, 05:51 PM
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How I made my oil-burning, pinging, clattering 3.8 purr like a kitten.
I'm sharing this because I know that like myself, many of you have/had problems with the 3.8L burning excessive oil, pinging and just generally not running well. It took me 2 1/2 years and 55K miles but I think I've resolved these problems to my own satisfaction. To make a long story short, I stopped reading the owners manual and started "listening" to what my jeep was asking for.
First the issue of oil consumption- Like many I used 5W-20 until my warranty expired and just kept adding oil every 500 miles or so. When my warranty ran out I changed to 5w-30 and then 10w-30 trying to reduce the oil burning. I changed the PCV valve. I tried Dino and synthetic. The thicker oil helped some but I was still burning as much as a quart every 1000 miles, especially with 5w-20 and maybe 3/4 qt with 10-30. Today I just completed my own 1000 mile test running a hi-mileage 10w-40 dino oil. My oil consumption was not measurable. When I filled it 1000 miles ago I took a file and notched my dipstick. Today at 1011 miles later the oil is still up to the notch. So it appears 10w-40 curbed the oil consumption pretty well. Furthermore the engine is running very smooth and quiet on 10w-40. I can run up to 4500 rpm between shifts and its has a bit of of throaty growl now instead of sounding like its going to fly apart. No more valve train clatter at idle either.
Second the issue of the pinging- At best I'd get a little pinging around 2300 rpm in the past. At worst the thing was practically undriveable. I know the owners manual says only use 87 octane, but I finally faced the fact that no matter what brand I tried, none of the 87 ( E10) gas in my area would produce suitable results. I took it to the dealership a couple of years ago and they said "bad gas" and did nothing about it. We'll I guess all the gas in Central Texas is "bad" then ( yeah right). I changed my spark plugs, installed a new knock sensor, wiped the memory several times by disconnecting the battery and other and some of the other things you may have read about. Finally a few months ago I did two rounds of Mopar combustion chamber cleaner, a can of BG 44K in the gas tank and a little while later switched to mid-grade 89 ( E10). The first round of combustion chamber cleaner helped alot, and the second helped even more. As long as a stay with 89 octane, from virtually any brand, even Walmart 89, it runs great. I mean it's like night and day difference over the past few months as compared to the last two years. The idle is also very smooth.
So in summary, I had good results by ignoring the owners manual, running 10w-40 and 89 octane after a good thorough fuel and intake system cleaning to clean our 55K miles worth of crud.
Disclaimers:
I'm sharing this because it worked for me, and you might like to know about it, for whatever its worth. Your results may vary. If you live north of I-40 where they have real winters, you might want to think twice about using 10w-40 in the winter. I'm no expert but it might not be wise in colder regions.
If your jeep is still under warranty, you may want to take that into consideration. You don't want to give Chrysler any reason to deny a claim. My jeep is not under warranty so I'm free to use it as my personal laboratory.
Also I need to tell you I ran 33 tires and 3:21 gears for the first 20K miles. I have no proof but my gut tells me that the resulting "lugging" of the engine accelerated the rate carbon build-up. My jeep ran better after I regeared. That was 30k+ miles ago.
Happy motoring and best of luck.
First the issue of oil consumption- Like many I used 5W-20 until my warranty expired and just kept adding oil every 500 miles or so. When my warranty ran out I changed to 5w-30 and then 10w-30 trying to reduce the oil burning. I changed the PCV valve. I tried Dino and synthetic. The thicker oil helped some but I was still burning as much as a quart every 1000 miles, especially with 5w-20 and maybe 3/4 qt with 10-30. Today I just completed my own 1000 mile test running a hi-mileage 10w-40 dino oil. My oil consumption was not measurable. When I filled it 1000 miles ago I took a file and notched my dipstick. Today at 1011 miles later the oil is still up to the notch. So it appears 10w-40 curbed the oil consumption pretty well. Furthermore the engine is running very smooth and quiet on 10w-40. I can run up to 4500 rpm between shifts and its has a bit of of throaty growl now instead of sounding like its going to fly apart. No more valve train clatter at idle either.
Second the issue of the pinging- At best I'd get a little pinging around 2300 rpm in the past. At worst the thing was practically undriveable. I know the owners manual says only use 87 octane, but I finally faced the fact that no matter what brand I tried, none of the 87 ( E10) gas in my area would produce suitable results. I took it to the dealership a couple of years ago and they said "bad gas" and did nothing about it. We'll I guess all the gas in Central Texas is "bad" then ( yeah right). I changed my spark plugs, installed a new knock sensor, wiped the memory several times by disconnecting the battery and other and some of the other things you may have read about. Finally a few months ago I did two rounds of Mopar combustion chamber cleaner, a can of BG 44K in the gas tank and a little while later switched to mid-grade 89 ( E10). The first round of combustion chamber cleaner helped alot, and the second helped even more. As long as a stay with 89 octane, from virtually any brand, even Walmart 89, it runs great. I mean it's like night and day difference over the past few months as compared to the last two years. The idle is also very smooth.
So in summary, I had good results by ignoring the owners manual, running 10w-40 and 89 octane after a good thorough fuel and intake system cleaning to clean our 55K miles worth of crud.
Disclaimers:
I'm sharing this because it worked for me, and you might like to know about it, for whatever its worth. Your results may vary. If you live north of I-40 where they have real winters, you might want to think twice about using 10w-40 in the winter. I'm no expert but it might not be wise in colder regions.
If your jeep is still under warranty, you may want to take that into consideration. You don't want to give Chrysler any reason to deny a claim. My jeep is not under warranty so I'm free to use it as my personal laboratory.
Also I need to tell you I ran 33 tires and 3:21 gears for the first 20K miles. I have no proof but my gut tells me that the resulting "lugging" of the engine accelerated the rate carbon build-up. My jeep ran better after I regeared. That was 30k+ miles ago.
Happy motoring and best of luck.
Last edited by HillCountry_Cowboy; 12-07-2012 at 06:18 PM.
12-12-2012, 03:38 PM
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Good info. Thanks for doing all this leg work. I am at 29k on my 11, and was waiting to hit 36k before going to 10w30. Good to know 10w40 is an option as well. I'm up in DFW.
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12-14-2012, 08:28 AM
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12-14-2012, 08:29 AM
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If I'm not mistaken an '08 has a 3.8L which is what the original poster has. The 3.6L is the new pentastar V-6...and that seems to have all its own issues.