JKlad

I notice the oil specification for the JK V6 is 5w20, and 5w30 as a substitute. I'm assuming they specify the low viscosity 20 in order to reduce running resistance and in turn increase MPG, but are there any other benefits running the 20, apart from in very cold weather?

For a low-tec, low-performance pushrod engine 5w20 seems to be overkill; I also had a mechanic budy scratching his head at the specification as here (in Australia) it would be purely a winter-oil spec for alpine regions on a motor of this design. The only vehicles running this oil as a summer spec would he high-performance, multi-valve turbos. Due to our hot climate here (summer temps even in Sydney regularly hit the mid-40's C (110+ F) most engines of the JK's design run 15 or 20w40.

I was buying oil the other day to do a change and the nearest I could get without placing an order was 5w30, and this was high-performance, fully synthetic racing oil that cost me 3 times what the regular 15w40 I use in my other car does. The reason I'm doing the change myself is that I've just hit 6000km (3500mi) and don't agree with Chrysler that the first oil change on a brand new, still running-in motor should be at 12000km (7500mi), synthetic oil or not.

Calypso

I've been doing the same research as you. It also gets very hot where I live and I agree that the 5w20 seems a bit thin. I have a good friend that works for Royal Purple and he recommended I go with 5w30 for our climate.

uwisuwerme7

I'd like to see what others are doing.
I just changed my oil for the first time myself since the dealer did it for free last time.
I noticed the dealer wrote that they used 5w30, but i made sure i got 5w20 since that's what the X says I need.
I live in South Carolina so from what the original poster is saying i may be someone who does need to be running 5w30.

ResQGrnRubi

I'l admit I'm running 5-20 year round, and a few years back, before I got the JK, we had 100+ days over 100°F. I'm doing it because the manual says to, I don't want to have engine probs., make a claim on the liftime warranty , and get caught with thicker oil, although I really want to run 10-30.

07JKX

i run 75w90 gear oil in my engine

uwisuwerme7

i bought mine used so i don't have the same warranty unfortunatly.

uwisuwerme7

But at the same time race motors are made to perform for a short time at their max potential and are usually expected to be rebuilt.

Chuck Bullitt

Technological advances in oil's lubricating abilities + the tighter tolerances in modern engines means you don't have to run the same 30 weight oil as you did in your 1970 Chevy.

5-20 will be just fine. I have two other vehicles that I've used the manufacturers recommended 5-20 oil, each with over 80K miles. Both still run perfect and my oil is still clean when I change it every 3K miles.

I live in a hot climate and 5-20 has never caused issues.

RedneckJeep

Me too! Imagine that. I find that adding just a tad of sawdust tends to help eliminate any extra noises.

07JKX

i had not thought of the sawdust i mix mine with KY to minimize the resistance... my jeep is naturally dry and needs a little extra somthin.... and if you use the warming liquid... your vehicle warms up faster! you gotta try it. its really good in the winter time if you do not have a garage!