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How much engine oil is TOO much??

J

jtszymano

NAXJA Forum User
Location
Aliso Viejo, CA
I know that the manual says the engine has a 6 quart capacity. I usually do 5.5 qt, but this time I just put it all in...a full 6 quarts.

Now, the dipstick puts me about a centimeter and a half above the full line. Should I dump a little bit or should It not matter. More importantly...what sort of problems could come from overfill??

Thanks JTS


I have the 4.0 L engine
 
Do you have any current leaks?
If you do, then it should't matter too much, but if you don't i was told overfilling can cause seals to bust. So it can get ugly.
 
thats the first I ever heard of seals bursting. The only thing I could think of happening is getting crappy mileage as the crank chops through more fluid.
I dump in 6 full quarts in routinely and have never had a problem.
 
Same here, I just dump in 6 quarts.
 
For those of you that put in the full 6 quarts...How far above the 'full' marker do you usually end up??
Im just trying to standardize the whole thing. Oh and what does the pressure usually run w/ the 6 qts? Thanks
JTS
 
Depends on what size/brand filter you use. On the factory mopars the level is a hair over the last hash mark, on the K&N its about the same, maybe a wee bit higher, the mobil-1 filter was quite a bit higher. I don't pay much attention as my corner circular driveway us all up hill or downhill, depends on whether you're coming or going... As long as it stays in the same spot between oil changes I'm happy.
 
I like my level betwen the marks, towards the high side...but I don't worry on a little overage as mine leaks. 1 cm over on mine is good for a few days w/o checking it.

on a tight motor, I'd rather run 'tween the marks than over.
 
Guys,

The owner's manual says the capacity is 6 quarts for my 88 XJ 4.0. I drive 7 miles over to my shop to change oil so it runs out warm, then install the new filter and fill with 6 quarts. I start it, check for leaks and close the hood.

Remember the dip stick is a piece of metal and not a micrometer calibrated to the National Bureau of Standards.

We don't know how much quality control goes into a dip stick so don't sell the farm yet. Before you start cutting back on oil i'd investigate your dip stick. If you have a buddy with an XJ or any Jeep with the 4.0 then swap dip sticks and see what it reads on the other. I think you will find your dip stick may me a little long vs your buddies.

Martin
 
I have always put in six and it comes up dead on the F mark. This is better than any of the other vehicles I've owned because all of them couldn't hold advertised capacity.
 
Just did both my 92 XJ's oil today and as usual I drain, do filter, add 5 qts., start up for a min., check level(my driveway slopes) and always add 1 more qt. Always 6 qts. for me. Heinz
 
I have always used a full 6 quarts, and it always comes right to the FULL mark on the dip stick. That's what the manual calls for, why in the world would you use less?

Yes, it is correct that overfilling can cause seals to blow out -- but putting in what the manual calls for is not "overfilling."
 
Yay, im not crazy in what i was told about seals blowing when overfilled.....I only said that b/c jtszymano thought he overfilled :). I dunno the capacity b/c i havent changed my own yet....
 
anyways even if for some reason you were full at 5.5 quarts. I doubt that the extra pressue of .5 of a quart would blow out a seal. When do you check the oil, before you first start it up after an oil change? if so that may be your reason, the filter usually is good for somewhere around half a quart or so depending on which type you use, so starting it up will fill your filter and may give you the right amount on your dipstick.
 
Thats interesting...I never knew that the filter was emtpy until you started it.

Well, I measured it when it was cold, ie, hasnt been started in 36hrs.

The only thing I did different was put a K&N, rather than the usual Mobil 1. Maybe Ill check it when its alittle hot and see where that leads me...
Ill follow up in a couple days...if anyone cares. But I imagine that this will come up again. So at least now there is a thread for the search fxn...

Thanks for all the help guys.
 
The only thing I did different was put a K&N, rather than the usual Mobil 1. Maybe Ill check it when its alittle hot and see where that leads me...


My guess is a little hot will get you about a quart low.

Change oil and filter run motor to circulate oil.Always check motor oil after engine has been off atleast 10 to 15 minutes for oil to drain back to pan where dipstick is located.Thats how gas stations used to push oil to unknowlegable car owners,the gas attendant would offer to check your oil and show the dipstick to you that it was low.
 
I've upgraded my 89 4.0 to the newer style filter adapter and this allows you to run a larger filter that stock. I've been running the Mobil M1 301 filter (similar to Fram PH8A, but a much better filter, go here http://www.geocities.com/motorcity/downs/3837/oilfilst.html)
for a few years and this larger filter allows for 7 qts of oil to be run. This has several benefits, the least being lower oil temps due to increased volume in system.
Happy Lubing.....

XJEEPER
 
you should always fill the oil filter with oil before installation, otherwise the engine doesnt get any oil until it fills the filter by itself. I learned this a while ago from a wise older mechanic and have never looked back, also it might help with erroneous readings because a filter will usually take a half of a quart.
 
How do I fill a fliter with oil that installs the way it does on an XJ? I don't know about your engine but my 4.0 has the bottom of the filter facing downwards. Gravity seems to be a problem... What's your trick?

Also, when you drain the engine of oil it's not like you get ALL the old oil out. The parts are still lubricated when you make that first start. The filter fills up in a matter of seconds so I doubt that it really matters much- the remaining oil should provide enough lube for the engine until the filter fills up.

As for the 6 quart thing. I dump in all 6 quarts and when I fire it up the filter sucks up just the right amount of oil to leave the XJ at the "full" line.
 
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