warpipe

I switched to 20 w 50 amsoil. much better

Ryan0260

Wow....I would say so. Thick stuff

JKlad

I think the main problem is that Chrysler attempts to cover all bases by specifying only one viscocity of oil (5W20, 5W30 if the former is unavailable) while selling this vehicle all around the world to a huge range of completely different climates. 5W20 (when used in the type of motor the JK has) is essentially a winter-weight oil designed for operating temperatures well below freezing up to around 70F, which covers Canada and most of the northern states of the US; hot climates, where temperatures typically range from 60F-110F year round require oil of a higher viscocity. The other reason Chrysler specifies this thin oil is that it returns slightly better fuel economy (<1MPG) on the 36hr bench test so they can achieve their government-mandated CAFE targets for the fleet.

Of course there will be the usual cries of "but modern full-synthetic oil has a much higher film strength and resists shear at high temperatures at lower viscocities than the old dino oils of days gone by" which is all well and good however Chrysler does not specify full synthetic, and the dealers and most owners simply fill it with regular cheap old dino anyway. And if anything, this dino does not protect as well at higher temperatures as cheap dino of 15 or so years ago as most of the anti-wear additives (zinc & phosphorus) have been removed for emmissions reasons as these wear out the cat converters prematurely (same reason why unleaded fuel must be used with cats as lead also kills them). For example prior to '97 1600ppm and over was the minimum phosphorus level commonly found however modern API certified oils have less than 600ppm.

Every other vehicle I have owned over the years will have a table in the owners manual specifying different oil to be used at different ambient temperatures, and I cetainly remember when I was living in Northern Germany a few years ago (which gets to -5F in winter and up to 105F in summer) having to drain the sump when the first snows arrived and put in low-viscocity winter grade oil while throwing on the snow tyres at the same time.

The owners manual of my other car (Mercedes) for example has a chart that lists no less than 5 different recommended oil viscocities depending on the ambient temperatures the vehicle will be operating in (I don't have my camera on me at the moment to take a picture of the recommended engine oil chart, but I will later & post it) and they are the following:

-4F & under to +14F: 5W20/5W30, -4F to +50F: 10W30, +32F to 86F & over: 20W40/20W50, year-round miltigrade oil: -4F to +86F & over: 10W40/10W50, +5F to +86F & over: 15W40/15W50.

As my mercedes never sees temps below 40F but frequently operates for much of the year at ambient temps of 100 to 110F, my mechanic actually uses 20W50 as it's fill. As I said in a previous post, every other vehicle where I am that has the same design of motor as my JK (old-school iron block, pushrod, low-output 60 degree V6) has 15W40 as it's specified fill due to our hot climate and general lack of sustained freezing winter temps outside the alpine regions, & that's exactly what I'll be using now my warranty's up. Guys is my Jeep club who run 15W40 all report their motors run quietly, extremely smoothly, don't ping, and use absolutely no oil between changes so I'm sold.

Ryan0260

Yes and I believe the 3.8 was originally designed to use 10w30 and no major changes were made to accept the 5w20. Add to that sloppy tolerances and bad quality control and its no surprise these things burn so much oil. These motors obviously need thicker oil but yes you are right that climate and temperatures definitely dictate how different viscosities perform

andrewbram

Is this the same 3.8 that was put in pontiac grad prix also. I used to have one and it had a gasket go bust. I ask because it was great motor with a common problem. Btw i am new owner of 2010 unlimited. Looks like i need to start keeping closer eye. Does any one know if its affecting 2010 and newer. I have read lots on it and from what i see its 2009 and older. Any thoughts on this?

Stepsride

After reading this thread i think the best answer is just monitor your oil levels ever 1000 miles or so. There is no rhyme nor reason to who has and who does not have this problem

grayandashleyunlimited

Definitely monitor it. I had no issues in my 2010 jku, but my 11 is burning oil, one quart every 3k. So I have changed to 5-30 in hopes it stops..

STCjpr

Have had several JKs that hemorrhage oil unmercifully- changing to 5w30 helped, though 10w30 stopped it altogether. Now I'm in a 2012 with a Pentastar and NOT looking back.

However, my wife's 3.8-powered '08 Town and Country with 40k miles is now burning a good 1.5-2 qts every 1k miles. Under a consumption test with the dealer now, and for whatever reason they filed a groove on my dipstick to show where the oil level was when they filled it- worth noting, it was RIGHT where it should be on the dipstick.

As I've told my wife, thankfully I bought a lifetime MaxCare warranty with this POS. I'm either going to drive it until it locks up (typical 3k oil change interval usually ends with the oil light coming on)(I'll top the oil off, then call a tow truck), or the dealer won't feed me some line this time about how 1.5-2qts lost isn't deemed 'ok' by Chrysler, and will just replace the block.

Ryan0260

I think what it comes down to is quality control. That's why some have the issues and some don't. Obviously something wasn't done right on the consuming motors

Stepsride

You are inferring that there is quality at Chrysler