Surf City Dan

Not to beat a dead horse on this subject but I just did an oil change today and I put in 10w-30 instead of the recommended 5w-20. I'm completely amazed right after start up just listening to the motor. My Rubi has 52000 miles and had the normal loose ticking sound that came from these motors. Not anymore!! Just by stepping up to a slightly thicker weight oil the motor sounds tight and quieter. It gave me a huge confidence boost just listening to it running. No more sewing machine noise. I've heard all the stories of Chrysler recommending the 5w-20 for EPA purposes and mileage. But I personally believe these motors will last longer on thicker oil like 10w-30. I TRULY WISH I DID THIS CHANGE EARLIER..

Cheapsk8

I just got an 09 rubicon and was reading the owners manual when it said to use 5w 20. It kind of confused me to use a oil like that in a v6. Anyways owners manuals are made by engineers not the people who drive them in my opinion.

RHD-Manx2

I use 10w-50 from the first oil change! Much better protection imo.

Sigman

I been running 5 W 30 since I did my first oil change. Now with 59,000 still very happy.

thirstypirate

I just made the switch to 10W-30 yesterday. 70k miles but this is only the second oil change since I've owned the Jeep.

grayandashleyunlimited

I too have made the switch. 5w30 was not quite it for me, (it was still better than 5w20) I know that 10w30 is just a different cold weight but, I can certainly feel a difference and hear one too. For sure I am going back to the old school 10w30 in the winter and 10w40 in the summer.

Dronac

I'v been using 5w-30 since my original engine spun a bearing under warranty. I also ran oil anaysis tests on my old oil samples to prove that 5w-30 does not hurt the engine. I'm probably going to try a fill of Rotella 5w-40 this weekend just to see if it protects any better. I'll post results of the lab tests on the oil in about 3-4 months.

WhosUrBuddiee

I wouldnt put anything in other than what they recommend. If something ever happens to your motor and you have the wrong oil in it, they can easily refuse to warranty it. Plus all my oil changes are free anyways, so I dont even pick.

Dronac

That's a good point for those still under warranty. We are getting to where lots of users no longer have any sort of warranty though. Also, 5w-30 is reccomended by Chrystler for the 3.8 in every market but the US. IMHO, it's an attempt to sacrifice longevity for MPG. Even half of 1 MPG makes a big difference to fleet MPG numbers. Motor oils have come a long way so today's 5w-20 is far better then 5w-20 a few decades ago, however, the same can be said for heavier oils.

JKlad

10W30 is what this motor was originally designed to run on. Then somewhere along the line, after the motor had been in service in the minivan fleet for some time, Chrysler reduced the specified weight to 5W30, and then reduced it again to 5W20 when this motor went into the then new JK Wrangler.

Chrysler did not make any major changes in design specs or internal tolerances to account for the change to this drastically thinner oil which is why these motors consume oil through the PCV system and past the rings and suffer carbon fouling in the combustion chambers, excessive pinging, blocked cats & failed O2 sensors, and many other issues associated with oil burning (including spun bearings if the sump is allowed to run dry due to this high oil consumption going unchecked). Chrysler reduced the oil weight specification for the Wrangler-fitted 3.8L V6 to 5W20 purely for mileage reasons and nothing else (when these motors are given the 36hr bench test they produce slightly better mileage figures [as in <1MPG better] running the thinner oil and thus help Chrysler to meet it's federally-mandated CAFE mileage targets for the fleet), and know very well that it results in high oil consumption which is why they claim oil consumption of one quart per 1000 miles is "acceptable". To make matters worse, Chrysler has designed the Wrangler's cooling systems to run very hot (helps with fuel efficiency) which puts further stress on this low-viscocity oil, particularly under extreme operating conditions (towing, climbing mountain passes at high RPMs, extended idling in stop-start traffic in hot weather, etc)

I myself started using 15W40 recently (I'm in a hot climate so could afford to go a slightly higher viscocity than the 10W30) and the difference to my motor was immediate. It stopped consuming oil immediately and no longer pings under load, and now purrs along smooth as silk without any of the rattles, knocks and ticks that I had previously become accustomed to. In addittion, the oil I now use conforms to the older (superceeded) API SL specification so it contains an additive package full of the anti-wear additives (namely phosphorus in the form of zinc di-thiophosphate at around 1100ppm) that the latest "emmissions control-friendly" API oils do not have (these additives are known to wear out the cat converters slightly quicker so have been phased out of the latest API spec oils, however without them lubrication systems suffer increased levels of shear and wear out far quicker & produce more emmissions in the end anyway).