So i have a 2002 jeep grand cherokee 4.0 i-6 with 70,000 miles on it, the car is MAYBE driven 4-5 times a week (short tips). So the last 3 oil changes i have done have been with synthetic (pu, synpower, and now edge with syntec) and i have noticed that after the oil change the oil turns a pale grayish color and then after a short time (1000-2000 miles) the oil is dark dark black. i have been doing short 3000 mile oci's with the synthetic just incase the engine may be sludged, but i have been cutting open the filters and they had no gunk or crud in them and when you look down through the valve cover hole the metal looks fairly clean. any idea's why the oil is getting so black so fast like this???
Jeep with black oil
- Thread starter trabuccomlfrd
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The oil is just doing its job of cleaning.
Both my 4.0 Jeep GC's turn oil dark fairly quickly. After about 3K the oil is dark brown color. However both my 96(100k) and 94(330k) are both super clean. The 96 is spotless under the valve cover and the 94 has a little varnish but overall VERY clean. I have been running Rotella 5w-40 for 7-8k intervals.
Black has many potential causes...my MB 240D would turn the oil black in a few hundred miles...carbon from the blowby...nothing wrong with the engine...or the oil at that point.
Color is interesting...but not definitive...
Color is interesting...but not definitive...
Originally Posted By: quietriot
just wondering why oil turns black?
obviously oil turns black, but ive never seen oil turn black after a 1000 miles, in my sierra the oil doesnt turn that color until ATLEAST 5000 miles on synthetic.
just wondering why oil turns black?
obviously oil turns black, but ive never seen oil turn black after a 1000 miles, in my sierra the oil doesnt turn that color until ATLEAST 5000 miles on synthetic.
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well he said he takes alot of short trips. That's probably the main culprit. You get more blowby on a cold engine plus the oil filter is in bypass mode most of the time because the oil isn't warmed up enough to flow through as easily. If you ran it down the highway for a couple hours it would probably look a little cleaner. But I wouldn't worry about it. I wouldn't start worrying until the day you pull the dipstick and it looks like a milkshake. (oil and coolant mixed=bad juju).
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oh if it makes you feel any better my oil turns black by the time I get out of my driveway after a change.
Fuel will turn it black. Gas mileage normal? Air filter clean?
Originally Posted By: ChiTDI
Fuel will turn it black. Gas mileage normal? Air filter clean?
gas millage sucks (14-15) and i always maintain a clean airfilter. i cleaned out the throttle body very good a year ago, and i have also seafoamed it.
Fuel will turn it black. Gas mileage normal? Air filter clean?
gas millage sucks (14-15) and i always maintain a clean airfilter. i cleaned out the throttle body very good a year ago, and i have also seafoamed it.
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I`ve always thought,that if when you change your oil,no matter now dark it drains,as long as it wipes off your hands totally clean,then the oil is doing it`s job keeping the contaminants in suspension.
Thick and dark is the problem, while draining used oil. Not likely to tell on the dipstick only if it's sludging to that point, but potentially. If it just looks like really dark oil, it's probably just in a typically unclean engine. There are some youtube videos of an older Jeep using a top-end cleaner, he must have ran it twice in the same year and it smoked for a long time while expelling the cleaner along with whatever it helped clean. I'd imagine your relatively newer model similarly has blow by etc.
Originally Posted By: trabuccomlfrd
Originally Posted By: ChiTDI
Fuel will turn it black. Gas mileage normal? Air filter clean?
gas millage sucks (14-15) and i always maintain a clean airfilter. i cleaned out the throttle body very good a year ago, and i have also seafoamed it.
Might want to have the fi system checked then. Perhaps a leaky injector or fuel pressure regulator not holding. Any starting issues?
Originally Posted By: ChiTDI
Fuel will turn it black. Gas mileage normal? Air filter clean?
gas millage sucks (14-15) and i always maintain a clean airfilter. i cleaned out the throttle body very good a year ago, and i have also seafoamed it.
Might want to have the fi system checked then. Perhaps a leaky injector or fuel pressure regulator not holding. Any starting issues?
I have a 2000 Jeep GC with the I6, and it USED to turn black really fast. Here's what I did: I was using Synth. 10W30 oils, Mobil1 and QS mostly, various brands, it still turned black quickly every change. I added some MM Oil, about a quart,(it was about 1/2 qt low at the time) ran it about 500 miles.
Upon draining, it was super black. I then ran a new oil chg, with MM about 1/4 qt, and changed it after about 4,000 miles. Very black but more towards dark brown. Then I put in Penz Platinum 5W30, with MM oil again, and it was very dark. The next change now, is PP 10W30, no MMO, and it did Not turn black quickly! It is now almost 7,000 miles, and only brown, not black, and the valves look very clean. I now believe that PP will clean your engine up well. I have about 113,000 on mine, and recommend the 10W30 PP.
PS - I used mostly the ToughGuard filters, now am using a Purolator. Didn't really notice much difference...
Of course YMMV, but I am very happy with PP in that engine. I plan to change it soon, and keep using PP. The Mobil 1 turned things a light brown, now that is mostly gone.
VW
Upon draining, it was super black. I then ran a new oil chg, with MM about 1/4 qt, and changed it after about 4,000 miles. Very black but more towards dark brown. Then I put in Penz Platinum 5W30, with MM oil again, and it was very dark. The next change now, is PP 10W30, no MMO, and it did Not turn black quickly! It is now almost 7,000 miles, and only brown, not black, and the valves look very clean. I now believe that PP will clean your engine up well. I have about 113,000 on mine, and recommend the 10W30 PP.
PS - I used mostly the ToughGuard filters, now am using a Purolator. Didn't really notice much difference...
Of course YMMV, but I am very happy with PP in that engine. I plan to change it soon, and keep using PP. The Mobil 1 turned things a light brown, now that is mostly gone.
VW
I have to agree with VW above; my use of PP 10w30 on the last couple of oil changes produced the same results he posted.....no blackness until the very end of 3-4k miles. Otherwise, it was always semi-clean or slightly brown.
This is the only brand that stayed clean until the end, which I have used. I also use Toughgard or Purolator filters & have not noticed much difference.
Whenever I used Valvoline conventional or Havoline, it always went black before 1000 miles.
Also, the motor seems to run 8 to 10 degrees cooler with PP, and also gets better city mileage...about 19 mpg.
Have you run Seafoam through your brake booster (which goes through your vacuum system) to clean out any garbage inside the motor? I did a couple of years ago & runs MUCH better.
GL
This is the only brand that stayed clean until the end, which I have used. I also use Toughgard or Purolator filters & have not noticed much difference.
Whenever I used Valvoline conventional or Havoline, it always went black before 1000 miles.
Also, the motor seems to run 8 to 10 degrees cooler with PP, and also gets better city mileage...about 19 mpg.
Have you run Seafoam through your brake booster (which goes through your vacuum system) to clean out any garbage inside the motor? I did a couple of years ago & runs MUCH better.
GL
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that jeep had spun a bearing thats the problem
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