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Discussion Starter #1
I must confess I have not changed my oil since I was 19 years old and poor. But now I'm back under the hood (per se) because I am sick and tired of the local Oil/Lube jocks diagnosing some "problem" with my Jeep every single time I take it for some clean oil. So the story begins like this ... I whip out the owners manual to find out how much oil my Jeep takes (3.7 L PowerTech V6) and it clearly states it takes 5 quarts if 5w30. Now for the drama ... I pull out my receipts from the oil change place to "confirm" the amount of oil needed for the Jeep and the receipt shows they've been putting in 6 quarts of oil! Now we all know putting more oil into your engine does not produce any benefits (like putting in more gas) ... to the contrary it can cause a great big headache! So after talking to the owner of the oil change facility it is decided that his employees have been over charging me for one extra quart of oil, but not actually putting the extra quart in ... nice huh?!?!

Now the reason I have turned to you guys ... what harm, if any, can come about from having an extra quart of oil in the engine during the past 4 oil changes? Since I changed the oil myself this last time the Jeep runs like normal ... actually my mileage has improved back to 17 mpg .... and I have noticed a little extra vibration at start up (sound like a clip is loose) maybe it was there before but never noticed.

Any insightful insight would be appreciated.
 

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The excess oil in the oil pan would cause more drag as the crankshaft is rotating thus needing more energy to maintain rpm's meaning less efficiency. The crankshaft connects to the rods which connects to the pistons. It is analogous to walking through ankle deep water and waist deep water, more energy is required to maintain the same speed in the waist deep water. This is probably why your mileage has increased and so should the responsiveness and overall performance. This does not mean you should put less oil in than recommended however. The one extra quart is a minimal difference and should not have any adverse effects if it was in for a minimal time period.
 

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To much fluid can cause problems with seals whether it be oil, tranny fluid or other. However IMHO if the excess was too excess it probably would have shot out somewhere where you would have seen drippage etc. Incidentally, the 4.0L 6 cyl engine takes 6 qts, I am sort of surprised the new v6 only takes 5. john
 

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Discussion Starter #4
John said:
To much fluid can cause problems with seals whether it be oil, tranny fluid or other. However IMHO if the excess was too excess it probably would have shot out somewhere where you would have seen drippage etc. Incidentally, the 4.0L 6 cyl engine takes 6 qts, I am sort of surprised the new v6 only takes 5. john
Unless my owners manual has a misprint in a very important section ... then all 2006 Red Jeep Commanders with a 3.7 L PowerTech V6 take 5 quarts of 5w30 ... if this is wrong please correct and site documentation.
 

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another issue with overfilling your crankcase is that when the crank throw hits the oil bath (which it won't do at normal levels) the oil will foam up. this will create air bubbles in your oil galleys and can cause premature bearing failure.
before you get all excited and worried, this doesn't cause too much of a problem under normal driving conditions. it will under heavy high RPM usage. i don't think i would worry too much about it but you may want to document everything just in case there is a problem down the road.
 

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I was only making a comment regarding 4.0L inline 6 engines that Jeep used until recently. Follow your owner manual.
Seperate question regarding oil change:
I am in a quandry. I always use total AMSOIL products, but now I have a coupon from the dealer for a very reasonably priced oil change including MOPAR filter. I am THINKING of taking advantage of it using AMSOIL oil but the MOPAR filter. Reason being the Amsoil filter is very expensive and designed to be used up to 15k miles though I change my oil every 6k miles. My question is, is the MOPAR oil filter any good filtration wise for 6k miles?? I will continue to use the AMSOIL oil. This is the Hemi engine. john
 

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my 2 cents....
Stick with the amsoil. I don't use amsoil but what would you do with the few $ that you save? Probably nothing significant.... I know I wouldn't. I think piece of mind is worth it especially since your not changing you oil every 3000.
 

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John said:
To much fluid can cause problems with seals whether it be oil, tranny fluid or other. However IMHO if the excess was too excess it probably would have shot out somewhere where you would have seen drippage etc. Incidentally, the 4.0L 6 cyl engine takes 6 qts, I am sort of surprised the new v6 only takes 5. john
Thats because the 4.0L six cylinder is an inline 6 or I-6, so compared to the V-6, it has a longer oil pan and therefore, holds an extra quart of oil. As for your problem, I agree with what "yanser" said. Did they refund your money for the extra oil and lost gas mileage? That's what I would be PO'd about. I wonder how many of their other customers were overcharged? What place was this?
 

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I hate all of those places!!! I do it or have my buddy that works at a small shop do it.
 

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Discussion Starter #12
blinkgold311 said:
Thats because the 4.0L six cylinder is an inline 6 or I-6, so compared to the V-6, it has a longer oil pan and therefore, holds an extra quart of oil. As for your problem, I agree with what "yanser" said. Did they refund your money for the extra oil and lost gas mileage? That's what I would be PO'd about. I wonder how many of their other customers were overcharged? What place was this?
I hate to kall {wink} this place out, but it's right in the middle of Pflugerville, TX ...
 

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Discussion Starter #13
NMRealtor said:
Could it be the oil filter taking up some or most of that 6th quart?
I could be wrong, but if the oil filter "needed" it's own oil in addition to the oil you put into the engine ... wouldn't the owners manual state this? I mean, we're talking about a "secret" quart of oil if that's the case then EVERY car ever made would require this extra oil ... right? no? yes? maybe? anyone ...:D
 

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I just had mine in for an oil change this morning....my dealer does it cheaper than those quick change places anyhow....looked at the 2008 Commander while I was there too....Not enough has changed to make me want to sign papers for a new one just yet :D
 
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