What's up with my oil pan (or engine)?

[dance_party]

Yesterday I changed the oil in my 2000 TJ (4.0 engine) for the first time since I purchased it from a local dealership. When I brought it home back in August, I noticed that the oil was overfilled quite a bit, so I drained some until I read the appropriate level on the dipstick. At that time, I also noted that the oil drain plug needed some help, so I purchased a replacement on Rockauto in order to have it on hand when the time came to actually change the oil.

Well, yesterday after draining the oil, I discovered that the 1/2-20 drain plug I had bought was too small. I checked Rockauto again, and noted that all of the plugs they sold for my year and model are 1/2-20... so I took the drain plug I had removed to Auto Zone and purchased one that was the correct size for the oil pan I'd taken it out of (M14-1.50).

At this point, it seems pretty clear that I don't have the stock oil pan, given that the drain plug is a different size and that the dealership overfilled it (probably expecting a 6 quart capacity). I put 5 quarts in, which came up right to the middle of the "SAFE" area of the dipstick. To the best of my knowledge, I've got a 4.0 engine (I've got the decals and VIN for one, anyway).

The question is... should I leave the oil pan alone, or replace it with a factory one?

Here's the top view of the engine... looks like a 4.0 to me (but I'm pretty new at the Jeep game):

 

[Jerry Bransford]

I'd leave it as is and when refilling in the future, add six quarts. Top of the full line is where you want it. Being in the middle of the 'safe zone' indicates it's down a half-quart.

 

[Jramos013]

I would not wait so long between oil change intervals, its been 7months since august. I usually do 3months or 3-4k miles, whichever comes first.

As for your original question, i would leave the pan alone and just get a plug that fits. Its not worth it to change the whole pan just for a bolt that can be change.

 

[dance_party]

Thanks for the quick responses. I'll top it off and not worry about the pan.

 

[Apparition]

I would not wait so long between oil change intervals, its been 7months since august. I usually do 3months or 3-4k miles, whichever comes first.

As for your original question, i would leave the pan alone and just get a plug that fits. Its not worth it to change the whole pan just for a bolt that can be change.

I’m lucky if I change my oil in some of my vehicles once a year, where’s this time requirement come from?

 

[Jramos013]

I’m lucky if I change my oil in some of my vehicles once a year, where’s this time requirement come from?

FSM....

 

[Apparition]

FSM....

View attachment 144981

LoL

 

[onoffroad]

Someone probably stripped the pan out and just tapped the pan out bigger to fit a 14x1.5m plug.

 

[BAPilot2]

Someone probably stripped the pan out and just tapped the pan out bigger to fit a 14x1.5m plug.

I agree.
The picture of your pan looks identical to the pan on my 2005.

 

[dance_party]

Someone probably stripped the pan out and just tapped the pan out bigger to fit a 14x1.5m plug.

That seems like a reasonable explanation.

 

[Mjv]

X2. Common repair for stripped o/p plug.

 

[Lyle]

The drain plug seal on my TJ began seeping last oil change. It's hardened up and lost all pliability, so naturally I went hunting for a new one. I too discovered that the drain plug on my TJ is a non-standard size, having 13mm wrench flats, a thicker shank, and 14tpi. In 10 years if ownership I've never questioned it until now, and you guys have solved the mystery for me. THANKS! Guess I'll have to order a non-standard plug and gasket before next oil change.

 

[Mike_H]

I put a replacement pan on mine due to rust and it is also a M14 thread. I believe the brand was spectra. Other than that, I can find no other differences

 

[Lyle]

I put a replacement pan on mine due to rust and it is also a M14 thread. I believe the brand was spectra. Other than that, I can find no other differences

Thanks for the info Mike_H