I do some occasional maintenance on an old coworker's 2000 Jeep Grand Cherokee with the 4.7L (141k miles). I planned to change the oil in it today. When I picked it up at his place, I noticed the oil pressure was steady at only 20 psi. I was a little alarmed but limped it the 1.5 miles to my house, maxing it out at 1400 RPM.
Before I pulled the plug, I wanted to see how much oil was in it. It didn't register on the dipstick. Only after I'd added 2.5 qts. did it finally register. I ended up adding about 3.25 qts. and still didn't quite get it to the ADD mark. (This was some used oil I'd drained after a 1000 mile run last year. Caught it in a clean pan and stuck it on the shelf for potential top-off oil.) I started it again and the oil pressure was then normal.
I went ahead and drained it and changed the filter. I didn't notice any obvious signs of major leaks and his driveway is clean, too. The last oil change was about 5500 miles ago, in May 2017, at a Jiffy Lube. When I filled it back up with just under 6 qts. of Chevron Supreme, the oil pressure stayed right where it should be.
As best as I can tell, the Jeep was running with 40-45% of the sump capacity. I opened up the filter and found some metal flakes, though not as many as I expected. The one I picked out and felt had a consistency similar to that of tin foil.
I also figured out his oil warning light on the dash is burned out. That doesn't help, but the oil pressure gauge was still an obvious tell that he and his wife completely missed.
Anyway, I've never been around an engine neglected like this. So I've had a few questions rolling around in my head:
1. My best guess is that the Jiffy Lube didn't get enough oil in there and this family drove the car for 8 months with a low oil level. If Jiffy Lube DID get it filled, what is going on in this engine to burn more than 3 qts. over 5550 miles?
2. Given how little oil there was in the engine, what was the effect on the oil that was in there?
3. Any guesses as to what the flakes in the filter used to be?
4. How much life did they take out of this engine? (I know this can't be answered in specifics.)
5. How close was this thing to seizing?
Jeep 4.7 run with 45% oil capacity for months
- Thread starter HawkeyeScott
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I've seen a Dodge 3.9 (Dakota) and Buick LeSabre (3800) run with 1.5 qts. in them, and a Caravan 3.8L run continually, repeatedly with 2 qts. in it. All 3 engines have come out of it seemingly unscathed - not to say it didn't shorten their lifespan, but in all cases that was months or years ago and they only detectable negative effect is continued oil consumption. It may just be using that much - they need to check it periodically. If they're not inclined to do that, they can enjoy the fruits of their labor when it does run dry.
our 4.7 used no discernable oil; but I certainly have owned many cars where a quart every 1500-2000 miles was not unusual. (american 4 cylinders)
after my experience last week with a neighbor ( 4 qts low ) it is clear that people do not check their oil level. if you don't know how, stop by once a month and have someone check. I'm pretty sure that Jiffy lube will check it and even top it off for free with the first 3k miles after a change. at least they used to...
That’s a high-mileage 18 year-old engine that wasn’t especially great when it was new. It sounds like it hasn’t been maintained well either. This is my cynical nature, but that thing is not long for this world. Don’t put yourself in a position where you’ll get blamed for its failure.
Even a 4.7L SOHC V8 can be properly lubricated by ~2 quarts. The gauge on the dash is fake. It reads 20lbs when it has 12v. There's an electronic pressure sender that is an on-off switch (I'm serious). Oil pressure COULD have been only a few PSI lower than spec and that would be due to oil thinning.
Don't overthink it. If it runs good and you could not find any discernable damage in the filter, then there's no discernable damage.
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With the 3.7 version, I know of a few people that ran about a quart (of a 5 qt capacity) and shortly ruined their engines. What's the capacity on the WJ? I want to say those were 6 or 7.
It might have just barely survived. I'm guessing it's a leaker, probably the valve cover gaskets, oil pressure sender, front main crank seal. These really aren't known for excessive oil consumption unless they've been abused (maybe this one). If they drive it a lot, it probably never collects enough in one spot to hit the ground. That's how my Liberty is, if it sits a few days I'll get a dime spot on the floor otherwise nothing.
My 4.7 will use about a quart over that many miles. But 4 qts low? I'd guess that they were shorted on the last oil change. Or that engine is already shot. One of the two. And BTW these do have a working pressure gauge. It's not like a Ford.
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The valve seals need replacing.
My SILs 3.8 Jeep was about 4 qts low when I started taking care of it for her. Substituted 0w40 in place of the factory 5w20 recommendation - problem solved.
The guy who owns a lot across the street has an old Camry 5 speed that he parks there to keep people from parking on the lot. Battery went dead so after jumping I had him pull it into my driveway and charged the battery overnight. The next morning I disconnected the charger and just for the heck of it checked the oil. Nothing on the stick. Took 4 qts to get to the stick and a full 5 to full. At least it got Edge 5w30, had a full jug laying around. After adding the oil, he came by, fired her off and drove away. Amazing.
Originally Posted By: DdDd
What's gonna happen on an 18year old vehicle worth 3k? Full rebuild?
The owner doesn't care. Top off the fluids and let them drive it into the ground. Somethings going to get it sooner or later
My anecdotes are:
1) SIL's 1995 Saturn held 4 quarts of oil. It had 3.
When I told her a few basics about oil (I drew a picture) she made a face that looked like I was blaming her for the treatment of Native Americans.
She promptly traded it in for a RAV-4.
2) Dear old Dad's 1985 Buick Regal wagon did not see an oil level check because I wasn't around.
I did an oil change and I think 24 to 30 ounces of thick, black stuff drained out.
That engine blew (lotsa steam, I was told, so I assume a head gasket) something like 4 years later.
Originally Posted By: Bandito440
That’s a high-mileage 18 year-old engine that wasn’t especially great when it was new. It sounds like it hasn’t been maintained well either. This is my cynical nature, but that thing is not long for this world. Don’t put yourself in a position where you’ll get blamed for its failure.
Originally Posted By: Blkstanger
My 4.7 will use about a quart over that many miles. But 4 qts low? I'd guess that they were shorted on the last oil change. Or that engine is already shot. One of the two. And BTW these do have a working pressure gauge. It's not like a Ford.
Classic neglect, I'm certain the neglect didn't do the engine any good. Maybe the owner is lucky and he won't have any issues as a result. I have my doubts.
Thanks everyone. I appreciate your thoughts on this. I hope they’ve learned a lesson without too much financial pain down the road.
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