Originally Posted by JKlad

Although some motors have had the rings incorrectly installed on the pistons resulting in huge amounts of oil consumption, it seems many JKs do burn some oil. We are told by Chrysler that this is normal.

The common consensus on my local forum where this discussion is currently running seems to be that it's the thin oil Chrysler specifies mainly to increase mileage for their CAFE figures that is the problem. Of course many people have said that modern, high performance, tight-tolerance motors need the new, thinner oils to lubricate themselves properly and the myth that the Chrysler 3.8L V6 is one of these modern, tight-tolerance motors seems to have propagated here. The new Pentastar quad cam, VVT, high performance V6 may certainly be in this category however the JK's old fashioned, iron block, low-revving, single camshaft pushrod motor 20 years or more old in design certainly is not. One of the guys is an experienced mechanic who has examined the specs for the JKs V6 motor and is of the opinion that the tolerances are decidedly old-school & not particularly tight at all.

In reality 5w20 is a low viscosity winter-weight oil that is well suited to the North American and European winter climate however under harsh operating conditions 20 weight oil will burn off in a motor such as the low-tech 3.8L V6, particularly at prolonged highway speeds. Many people where I am have found that their oil consumption stops completely when they switch to 15w40 grade oil, which is far better suited to hot climates (5w20 isn't even available off-the-shelf where I am as it's considered too thin an application for hot climates, 5w30 being the thinnest oil available without special order).

Originally Posted by JKlad

Although some motors have had the rings incorrectly installed on the pistons resulting in huge amounts of oil consumption, it seems many JKs do burn some oil. We are told by Chrysler that this is normal.

The common consensus on my local forum where this discussion is currently running seems to be that it's the thin oil Chrysler specifies mainly to increase mileage for their CAFE figures that is the problem. Of course many people have said that modern, high performance, tight-tolerance motors need the new, thinner oils to lubricate themselves properly and the myth that the Chrysler 3.8L V6 is one of these modern, tight-tolerance motors seems to have propagated here. The new Pentastar quad cam, VVT, high performance V6 may certainly be in this category however the JK's old fashioned, iron block, low-revving, single camshaft pushrod motor 20 years or more old in design certainly is not. One of the guys is an experienced mechanic who has examined the specs for the JKs V6 motor and is of the opinion that the tolerances are decidedly old-school & not particularly tight at all.

In reality 5w20 is a low viscosity winter-weight oil that is well suited to the North American and European winter climate however under harsh operating conditions 20 weight oil will burn off in a motor such as the low-tech 3.8L V6, particularly at prolonged highway speeds. Many people where I am have found that their oil consumption stops completely when they switch to 15w40 grade oil, which is far better suited to hot climates (5w20 isn't even available off-the-shelf where I am as it's considered too thin an application for hot climates, 5w30 being the thinnest oil available without special order).

Originally Posted by Flip94ta

I'm shocked nobody has done a compression test. You can get a tester for $25 at autozone. Anyone have a manual with the acceptable range? I'm thinking 150-200 psi would show on a healthy motor.

Originally Posted by angermgmt

We really should get a poll going comparing the engine ID numbers denoting location of assembly and respective dates.

Originally Posted by ronjenx

The knowledge to do that has been disseminated.

Only two people have bothered to look at their engine numbers, and post their engine's point of assembly.

Originally Posted by bulletproofjk

Reiper,
Let me get this right. You just had your jeep in to rebuild the incorrectly installed piston rings and now it's burning even MORE oil than before the rebuild?

Originally Posted by JKlad

I wonder did they just replace the rings without re-honing the block, as the damaged cylinder walls wouldn't take long to wreck the new rings.