holy_crap

I've had my 3.8L for 4 years, put 60,000+ miles on it and have had no problems at all, including the oil burning that some experience. I have used Mobil 1 oil and filter every 10,000 miles since new, I don't know if that is a factor in the oil burning case. My complains are not about the reliability of the engine itself, it is about the entire transfer of power from engine when I press the accelerator to the wheels. The current engine/transmission combination as others have stated is the issue with the perceived performance or lack of. I have an automatic with 3.73 gears, 3.5" of lift and 35" tires and a K&N drop in air filter.

Pros:
1) Engine is reliable and proven.
2) Fairly easy to work on, plenty of room.

Cons:
1) I average 13.5 mpg, I can never get above 15.5 mpg of all highway driving even when I drive it like a grandma.
2) I sometimes tow a 3500 lb. boat/trailer, I always turn O/D off when towing so I am limited to 3 gears, very often on the highway it fluctuates between 2nd and 3rd gear just to go over an overpass, this pushes the revs from about 3000 to 4500-5000 and it is constant.
3) Trying to pass a vehicle going 65mph is an exercise in patience.
4) That ticking noise that makes it sound like a sewing machine.

Bottom line is i never really disliked the 3.8, just wished it was better. This week after hearing that the next Wrangler model change will not come until 2018, I decided to test drive a 2014 Rubicon. BIG MISTAKE... The difference is very noticeable, especially at the passing range. WOW, now I really dislike my 3.8L...

planman

If you run with the OD off when you are not towing, your mpg will go up. The rpms would be the same as with 5.38 gears.

If you regear to 5.13s, both your in town and highway mpg will go up.

osubauer

So your saying that not using the OD will improve in town mpg? Wouldn't the RPMs go up causing the engine to use more fuel? I understand that typical in town driving usually never gets you into OD due to stop and go driving so in essence you aren't using OD anyway. If this is the case, how does disabling the OD improve MPG?

holy_crap

I will try this today and report back. I thought the O/D was to increase your MPG...

planman

Rpm does not equal fuel use.

You can bog down your engine with the accelerator at a greater degree of throttle and use more fuel at a lower rpm than at a lower level of throttle with a higher rpm.

If you have ridden a bike with gears, you would have experienced this.

If you pedal the bike up a steep hill or into the wind in a top gear at too low a pedal rpm, you will expend more energy than if you downshift and pedal the bike at a higher rpm.

Secondly, after the issue of bogging down the engine with too low rpms, the next issue is transmission downshifting.

When your transmission downshifts from OD to 3rd gear at speed, it flashes the converter. The transmission is allowed to slip in 3rd gear and it runs higher rpms at close to full throttle than it would if you were just in 3rd gear with the converter locked.

Try it. Drive a hill with the cruise control on that would normally result in your transmission downshifting. Take note of the surge in rpms in 3rd gear on the downshift that stay elevated until the set speed is reached.

Then, drive the same hill with the OD off and the cruise control set at the same speed. The converter remains locked and the rpms are less than they surged to when you did it with the OD on.

holy_crap

UPDATE: I've put on about 60 miles of mostly highway driving with the O/D off. Although I have noticed a difference in shifting behavior, I've actually decreased my MPG by about .5 so far. I will report back with the overall number after I use up this tank of gas to get a better comparison.

Chango

I never had a problem with my 3.8... it was a solid, albeit gutless motor.

But now that I've got a '14 I will never go back.

Mikek

Had it for nearly 3 years. 6 speed man, 2 inch lift, bull bar and huge spotties - zero problems and just chugs along fine. 6th gear doesn't get much use except on flat highway runs but who cares. Regardless of the 3.8 I get lots of comments from mates along the line 'wish I had one, looks great', It's paid for and does the job, great off-road and has lots of 'cool factor' (so says my sons) and the looks I get from other old blokes sitting beside me in boring soft-roaders are ones of pure envy - love it and will continue with it till it dies.

RickRumenysRedRubicon

My 2010 3.8 is fine. I didn’t buy my Jeep for speed. I bought it for a little off road fun, winter snow security, something fun to mod, keeps its value and good people to get advice and wheel with. No probs. So far. Not a drop of oil. If I wanted speed, Subaru evo, those hemi’S, even the jk s/c mods. I have a 1966 wrangler rolling frame and was thinking of a 3.8 s/c ford tbird motor mod.
RRRR

LOST

I really wish I had kept my 2007 X. It never broke down and went everywhere I pointed it.

My new Rubicon has been to the dealer 7 times for a total of 22 days for repeated cooling system failures.

Only has 10K miles on it and guess what....

Blew up radiator number 3 on the way to work today!!!

Yay. Trip#8, rad#4, 23 days and counting in the shop in 1 year.