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Engine Oil change for 3.8L

Changing the 3.8L Engine Oil

Part #:

I used the JK for this one, but the older 4.0L in the LJ, TJ, etc.. is not very different. This is routine maintenance for your Jeep. Very simple and practically anyone can do it. Now there are a few advantages to taking it to a shop or the dealership to do. I would recommend the dealership over a local shop just for the simple fact that they use the (at last check) better oil filters and they get to see your Jeep more often and are sometimes easier to deal with for warranty work. Everyone has their choice in oil, I generally use Mobil 1 oil and a Mopar oil filter for the Jeep. If I don't have any of those I go with a Mobil 1 oil filter. I have been told that the Mobil 1 M1-209 is a higher capacity filter that fits the JK. I have not verified this.

Additional Parts:
Oil of choice
--5w-20 for the 07-11 JK's
Oil Filter of choice
--Mobil 1 M1-102

Tools Needed:
Oil pan
Paper/ drop cloth
Filter Wrench
13mm Combo wrench
Ventless goggles


Change your oil:
1. Park your Jeep in a level area and put it in park (auto) or in gear (standard), set the parking brake. Remember you are crawling under the vehicle and will be positioning your body behind one of the tires.
2. Wipe off the area around the oil fill. Remove the oil fill cap and clean it off also.
Note: It is an OIL not a 710 cap. If you remember the Joke.

3. Wipe off the area around the oil dipstick. Remove the oil dipstick, wipe it off and put it somewhere safe. Most of us just throw it on the top of the grill by the radiator. Shutting the hood on the dipstick is not a good thing for the dipstick.
4. Gather up your supplies for draining the oil. Oil pan, rags, newspaper, or an old drop cloth and the fill funnel.
5. Wipe off the area around the oil drain plug. Lay out your newspaper or drop cloth, position the oil pan under the drain. Remember that the oil is going to flow out in an arc, so you don't want to center the pan under the plug, it should sit off center towards the rear.
Note: If your drain pan has a plug and a vent in it. It's a good thing to open both of these. Otherwise you will have a good use of the drop cloth or newspapers. Yes, I was not paying attention and left the drain in the center of the catch basin closed...
6. Put a pair of ventless goggles on. Remove the plug slowly with a 13mm combo wrench. The oil will flow out. While the oil is flowing, clean the drain plug off with a rag and take a look at the rubber seal on it to make sure it is not cracked.
7. Insert the funnel into the oil fill on the valve cover.
8. Once the oil has drained from the oil pan, reinstall the oil drain plug.

9. Remove the oil filter with an oil filter wrench. I have seen these on so tight that you need to get a big pair of water pump pliers on it, or even pound a screw driver through them to loosen them.

Note: The oil from the filter will manage to run along the engine, on top of axles, etc. They are a pain to not leak on everything.

10. Inspect the new oil filter to make sure nothing is down inside of it and nothing is rattling around inside.
11. Lubricate the rubber gasket with some new engine oil.
12. Wipe of any old oil from the oil filter engine mount. Ensure that the rubber gasket from the old filter is not still attatched to the engine. Carefully screw the oil filter on until it makes contact with the surface. Then depending upon your oil filter tighten it another 3/4 to 1 1/4 turn. Check your filter to see how far you are to tighten it, they are different.
13. The 4.0L and the 3.8L both use 6 qt's of oil, so pour in 6 qts to begin with. Check the level on the dip stick, it should be a little high. Check underneath for any leaks.
14. Start the engine and let it run for a few moments. Shut the engine off and restart it. Watch to make sure that the oil pressure indicator goes out or does not light depending upon your model and engine. The older ones even had a pressure gauge that actually worked. Shut the engine off, and check underneath for any leaks from the oil drain and oil filter. Check the oil level on the dipstick and top off with oil if required.
15. You can drain the oil pan into the jugs that you just poured the new oil out of and take the oil to a recycling center. Most autoparts stores have a tank in the back. My local Pepboys and Autozone does it, though my local Advanced Auto doesn't.

The 2008 and up JK's have an oil change reminder that comes on approx. every 3,000 miles. To reset this you will need to do the following.

1. Turn the ignition switch to the ON position (Do not start the engine).
2. Fully depress the accelerator pedal slowly three times within 10 seconds.
3. Turn the ignition switch to the OFF/LOCK position.

Note: I have been told that some of the 2007 late year models have this also.



  N-m Ft. Lbs. In. Lbs.

This page last updated: 05-Oct-2012

Content and Design © 2002-present WanderingTrail,  Ron Seegert
Common Sense and Safety should always be observed when working on your vehicle or doing modifications. Jackstands, wheel blocks, disconnecting the battery are a few of the basic safety precautions that should be used and may not be mentioned in the write ups on this site. You are responsible for your own installation, these write ups are a helpful guideline and should not be taken as an official installation instruction. My write up may be different from the kits currently out there, so alwasy double check the manufacturers installation instructions when installing anything. I try to keep the site up to date with changes that have occured as I discover them, but may not have the latest unless someone lets me know. If you feel that an install is above your capabilities after reading my write ups, I recommend getting together with a club and getting some help. Only a few times have I needed to employe some actual help from a shop to get something done. Usually welding or A/C work.
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