Chrysler changing oil spec Grand Cherokee 4.7 H.O.

[Turbo]

Need to change the oil in a 2004 Grand Cherokee with the 4.7 High Output Engine. Found some very interesting information and was wondering why would Chrysler change oil specs after a vehicle has been in service for six years? The factory service manual says 5w30 is preferred up to 100F and it is even labeled on the oil fill cap. In 2008 six years after this motor was first introduced they release a Technical Service Bulletin changing the oil spec to 5w30 for below 32F and 10w30 for above 0f. Why would they do this? Don't you think it is a little late in the game for such a change? Does anyone here know why this was done. The bulletin is basically saying we made a mistake. Why not run the 5w30 in the warmer weather especially if it is synthetic.

Here is the factory owners manual. Page 260 has the oil recommendations.
https://cdn.dealereprocess.net/cdn/servicemanuals/jeep/2004-grandcherokee.pdf



BULLETIN NUMBER: 04172008
TO: All Lubrication Guides Users
FROM: Specifications Team, Chek-Chart Data Acquisition
DATE: April 17, 2008

SUBJECT: Engine oil viscosity listed for 2001-08 Jeep Grand Cherokee and 2007-08 Jeep Commander

Please be advised that the engine oil viscosity as published in our Lubrication Guides is incorrectly listed in some occasions for the 2001-08 Jeep Grand Cherokee and 2007-08 Jeep Commander. The OEM recommended engine oil viscosity for the 2001-08 Jeep Grand Cherokee and 2007-08 Jeep Commander is listed below:

2007-08 3.0L Turbo Diesel All Temperatures - SAE 5w30

2005-06 3.7L All Temperatures - SAE 5w30

2007-08 3.7L All Temperatures - SAE 5W-20

2001-04 4.0L Above 0 degrees Fahrenheit - SAE 10w30
Below 32 degrees Fahrenheit - SAE 5w30

2001-04 4.7L Above 0 degrees Fahrenheit - SAE 10w30
Below 100 degrees Fahrenheit - SAE 5w30

2005-06 4.7L All Temperatures - SAE 5w30

2007-08 4.7L All Temperatures - SAE 5W-20

2002-04 4.7L High Output Above 0 degrees Fahrenheit - SAE 10w30
Below 32 degrees Fahrenheit - SAE 5w30

2005-08 5.7L All Temperatures - SAE 5W-20

2006-08 6.1L All Temperatures - SAE 0W-40

 

[Snagglefoot]

Very anomalous change for the 2002-04 4.7 H.O. Was it experiencing lifter noise?

The 6.1 using 0w-40 I understand. It’s a dedicated high performance motor and most likely will be driven hard.

Small typo for the 4.7. Should probably read below 32, not below 100.

 

[earlyre]

if you want to muddy the waters further, My brother's '07 Dakota has the 4.7 HO, it's manual calls for a blanket 5w20 across all temps and engine configurations.

 

[LotI]

Ford has done this too with the 6.8l V10 gasser. Up to 2015, they spec'd 5w-20 like all the other modular motors but then made a change to 5w30.

There were no changes to the engine with the switch to 30 grade oil and it's not retroactive. Since it's a HD vehicle they don't have to go through emission testing again.

I run a A3/B4 in mine.

 

[JLTD]

The TSB said error in printing which is certainly possible. Maybe also the long timing chains were shearing thee oil too rapidly?

 

[KCJeep]

They are trying to avoid too thin of oil due to shear. The 5w30's of the era were not as good as now, and even today you could reasonably expect less shear with a 10w30 over a 5w30.

The old 4.0 which I still own does not do well on thinner oils, and had the 10w30 recommendation right from the start.

I have run everything from 5w30 to SAE 30 and HDEO 10w30's in mine depending on temperature. I can assure you at temps above 20 degrees or so you will not likely notice the slightest running difference between a 10w30 and a 5w30.

In my Jeep, as long as it's above 45 or so, the SAE 30 starts and runs just like a 10w30.

 

[Garak]

Chrysler likes to complicate oil choices, I think.