Correct Oil for 3.8L Engine

[The Spook]

I have a 2009 petrol Wrangler with the 3.8L V6. Since new I have changed the oil and filter at the mid point of the service interval (every 6,000 kms) as well as getting it serviced at every 12,000 kms either at a Jeep dealership or by my local mechanic. The book specifies 5W-20 oil, but due to it being unavailable here in Canberra until just recently, myself and my mechanic have been using good quality 5W-30 that meets MB229.31 or MB229.51, as per the book. Now that 5W-20 has suddenly appeared on the shelves (Nulon, Penrite, LiquiMoly), it is worth switching to 5W-20 oil, given that the vehicle has done 130,000 kms and doesn't burn any oil? From what I have read, 5W-20 oil seems to be more about the manufacturer being able to meet Government imposed fuel efficiency regulations than protecting the engine from wear. Additionally, the other specs required by Jeep (ACEA C3, MB229.31, MB229.51) seem to relate to diesel engines and those petrol engines with very long service intervals (up to 20,000 kms). Seeing that neither of these apply to my engine, should I just keep using a good quality 5W-30, or should I go with the manufacturers requirements. Interestingly, the 3 times I have had the vehicle serviced by Jeep, they have used 3 different types of oil - 5W-40, 5W-20 and 5W-40 again, but from a different oil company.

Am I over thinking this? Are there any oil experts out there with some sage advice for me please?

[humdingerslammer]

Well, if u are not overthinking "this" u r certainly over changing it (the oil I mean) if u r changing oil every 6000km. Oil only needs to be changed every 12000km (I do mine every 10000km...humour me I am old) and I change the oil filter at the same time.

I usually use Magnatec 10W-40 or similarly rated other brand. 5-40 when it is on special at Repco etc.

[GrumpyOldPom]

Hi, I always use 5w-30 Castrol Edge. I live in Canberra also. I also change my oil every 6000km (and filter) in between services! When I do get it serviced I supply my own oil.

[Wazza D]

I've used Castol GTX 5W-30 since new. Don't care if it is the best oil to use or not, it works.
As far as intervals are concerned, correct me if I am wrong, but doesn't the handbook say somewhere, 12,000k or 6,000k under harsh or off road conditions?
I change mine every 6,000k by the way.

[The Beard]

I was running 5W-30 and Ryco filters but I tended to burn through it, plus I was getting a low oil pressure light at startup - then changed to 10W-40 and Mopar filters and the problem went away.

Any pics of your JK's about? I'm in Canberra too, probably seen you about at some point.

[milky01]

I run Nulon 5W-20 in my 2013 JK and so far so good. A bit wierd though as the 2012 with practically the same engine recommends 5W-30. I'd like to think 5W-20 gives the same levels of lubrication/protection as 5W-30 but with better mileage but difficult to know for sure.

[MightyMouse]

Its also interesting to note that the E series engine is a 25 year old design and in all but the JK ran higher viscosity oil. The change "somehow" coincided with the introduction of the CAFE fuel economy legislation.

They also weren't noted for high oil consumption.... which isn't the case now.

Does give you something to think about doesn't it ?