06 Jeep GC 4.7 - Considering going thin

Messages
17
Location
North Georgia
Hello all, I've been visiting the site on and off for many years and finally decided to register to ask some questions. Vehicle I'm asking about: 2006 Jeep Grand Cherokee 4.7 V8 (Not the same as the earlier Jeep/Dodge 4.7s that had more sludging issues) w/ 6 quart sump, 101k miles Driving conditions: About 10-12k a year during my ownership, quite a bit of suburban short/medium trips (8-15 miles) with longer highway drives pretty regularly. Pretty mild climate with winter temps usually staying above freezing, although cold snaps sometimes have me driving in 20-25 degree weather. Previous oil changes: Manual calls for API 5W30 meeting MS6395, but I'm well out of warranty, so not really concerned about the Chrysler spec since all the oils I consider likely either meet or exceed it, certified or not. I've been using M1 EP 5W30 for about 40k miles with no complaints, aiming for changes around 8-10k, but my last OCI was 12k due to bad weather and laziness. Started using M1 filters when I started using the EP, but last time I changed the oil I decided to go with a Fram Ultra that’s currently still on there and may stay on for another OCI. The oil in there currently has about 8k on it, and I've only had to add half a quart recently to get it back into the middle of the "safe" zone on the dipstick, where it was right after the oil change. Looking at changing it now while the weather is decent. Even though I know real cold weather isn't really a concern in my location, the significantly lower temps lately have me curious about possibly trying a thinner oil. I really doubt I'll see much difference one way or another, especially one that could be measured, but I'm an experimenter and all the "thin is in" posts over the years are certainly intriguing to an experimenter. The 2007 model year Grand Cherokee (and equivalent Dodge) changed oil spec to 5W20, with the reasons much debated online. I do not believe that there were any changes to the engines that year other than some V8 flex fuel engines being available. 2008 saw an updated V8 with significantly more HP and torque. So with all that being said, I'm thinking I should be safe using a 5W20 or even 0W20, right? Considering picking up some PP 5W20 at WalMart since it’s on rebate, or sticking with M1EP and trying out their 0W20. Yes, I know that a good conventional like PYB changed twice a year would probably be more than satisfactory for me and my conditions, but even if there weren’t rebates that narrowed or eliminated the cost gap, I still wouldn’t fret over spending an extra 20 dollars or so on an oil change, even if the benefits are mostly psychological. Any risks I should be concerned about going thinner, or thoughts on the oils I’m considering? Thanks!
 
Messages
13,087
Location
Indiana
Welcome! This sort of thing has been discussed with no definite answers. Realistically, you or your Jeep wont know the difference between a 5w20 or a 5w30.. That being said, Id stick with the 5w30 and sleep well at night especially in your climate. If you are really wanting to experiment, run some 5w20 and get a used oil analysis. It would be interesting to see the results. I am personally not a fan of going back on oil weights regardless of what other like engines are spec'd for.
 
Messages
2,011
Location
War Eagle
Hello and welcome I live up in the northern part of AL. Glad you decided to join the forum. You will get many opinions from your post. Most will be good and there are some really knowledgable folks around this site. There are some really good 0w30 oils on the market. They will be just fine in that engine as they will flow well in our temps and still have same spec as the engine calls for. Castrol has a really good 0w30 on the market. As far as experimentation, I have done that with my Jeep GC and my engine really does not seem to care what I put in it. Still going strong. Hope you enjoy the answers you get.
 
Messages
945
Location
Michigan
Ha, this thread is timely!! I just bought a 2005 JGC Limited with the 4.7l yesterday. I changed the oil today and refilled with Castrol Edge 5w30 and used a Purolator classic oil filter. Personally, my Jeep has 103,000 miles on it and I picked 5w30. Its what Jeep recommended back then and I had 2 jugs of Edge sitting in my garage just waiting to be used. I plan on doing 6000-7000 mile OCI's.
 
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Messages
8,130
Location
Mahzurrah!
If you mean "by safe" that your engine won't explode you are right. It would probably even be okay longer term but why? What are you trying to accomplish exactly? If you must tinker play with a 0w30 or a different 5w30. JMO.
 
Messages
3,117
Location
Virginia
I'd just stay with the M1 5W-30 you're already using. But I'm kinda crazy in that when I find something that works, I stick to it. So take my advice with a grain of salt, because many people on this forum love to conduct tribology experiments with their daily drivers. No big deal if they have to rent a car while waiting for an engine rebuild.
 
Messages
166
Location
near Montreal, Canada
I daily drove a 2004 Dodge Ram 1500 with a 4.7 for about 10 years. Very reliable engine, low HP numbers (240) but torquey (300 lb/ft) Poor gas mileage by today's V8 standards. Spark plugs every second year as regular maintenance, over the years the only repairs were 2 water pumps (loose bearing / leak). In Montreal Canada climate, experimented with 0W-30 once but got noisy start-up / lifter noises. Got best results with a 'thin' 5W-30 like Pennzoil Platinum. About the 'sludging' issues this engine often gets on forums, the PCV design / oil filler tube is problematic in cold weather operation, oil vapors cool off and "emulsify" in the fill tube and create a milky sludge inside. A simple fix is to remove the plastic fill tube from the engine (2-3 bolts) and wrap it with several layers of insulation tape to retain as much heat inside. I also threw away the 'baffle' that sits under the fill cap. After doing this mod I have never seen any emulsion build-up in the oil fill tube ever since.
 
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Messages
141
Location
Colorado
Originally Posted By: Quark
2006 Jeep Grand Cherokee 4.7 V8 (Not the same as the earlier Jeep/Dodge 4.7s that had more sludging issues)
Why do you say this is not the same as the earlier 4.7L?
 
Messages
945
Location
Michigan
Sooooo OP: What did you end up tossing in the engine?? Did the aluminum heads immediately melt and the connecting rods weld themselves to the crank and wrist pins the second you put a x/w20 grade in there? Inquiring minds would like to know!! lol
 
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Messages
697
Location
TX & ON
Throw a fill of Amsoil ATM 10w-30 in there and breathe easy. It flows better than most 5w-30s and has a very low vol at around 6.
 
Messages
35,785
Location
NY
I'd go with Mobil 1 0W30, I wouldn't use a 20 grade oil in that engine. Odds are you'll probably use more oil with the 20 grade and there would be no real benefit. Opinions vary.
 
Messages
8,598
Location
Florida
My mom has a 3.7 Jeep Grand Cherokee and I use 5w20. It works well. A 3.7 is basically a 4.7 with 2 cylinders removed and a balance shaft added.
 
Messages
17,541
Location
Upper Midwest
I love your posts, they are always well reasoned and supported with objective evidence. Well done.
Originally Posted By: Ram01
A 20wt will be to thin to protect
 
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