Should one only stick to 5W-30 in our 4.2 i6 ? (excluding extreme climates)

[Capote]

Been reading through some threads from the past couple of months concerning oil viscosity, consumption, what GM calls for, etc.. The consensus is to just run 5w-30, unless you're in an extreme temperature environment, whether it be a freezing climate or a very hot one. I live here in GA so technically I don't have either, just a more humid climate, which makes it feel hotter than it really is. I started to run T6 Rotella 5w-40 two oil changes ago as a recommendation from a friend who also had lifter noise at the time and seemed to reduce his after using this oil weight. I have noticed a difference vs. when I used 5w-30 in terms of noise; can't really say on consumption as I don't have a consistent schedule on how I do my fluid checks (mostly my PS fluid, since I've had a leak for a while). Is there any long term downsides to me having running this weight of oil for 6,000+ miles now since it's not what is recommended by GM for our 4.2 i6's. I recall someone saying 5w-40 doesn't provide as good lubrication as 5w-30 in our engines if that makes sense? Just wanting to get some better information here, seeing that some of you really know a lot when it comes to this subject matter. I'm not gonna lie, i'm not 100% on my oil knowledge, mostly common.

@Mooseman
@MRRSM

 

[Tiggerr]

I won't claim to be an expert on oil viscosity, but I'd think you'll be fine running that oil. Especially in GA. When I lived in East TX I ran 10w/40 in place of 5w/30 and had no problems in the 8-9 yrs I lived there.

The 5w would be the more critical number as far as it goes..thats the viscosity when cold, the 40 is after its hot. So the 5w/40 won't be too thick to flow when engine is cold..when it's hot the slightly heavier 40 is probably what's shutting up your lifter noises...40 vs 30 not a huge difference that'd be detrimental to anything...
If that all makes sense...

 

[mrrsm]

@Capote ... I'm with @Tiggerr on the idea that its the low number in the Oil Choice that makes all the difference on start up. But the GM Atlas 4.2L Engine has some additional hidden considerations that most engines never have to deal with relating to the "Change Oil Light" and the behavior of the Cam Phaser at all RPM ranges and the issue boils down to these problems:

(1) The Cam Phaser in this bizarre power plant is VERY busy in having to adjust the 25 degrees of variable timing during a very wide range of RPM... but especially at idle when the Gerotor Oil Pump is not cranking out a full boat load of 65 PSI and churning over 11 Gallons of Oil per Minute through the engine. As soon as the Oil Viscosity is bumped to a higher level... the sensitivity of the Cam Phaser to the changes in RPM is diminished and the problems that creates will play hell with the Timing Chain Set trying to maintain steady tension. It is important to remember that while the concept of VVT brings great power and flexibility to the Atlas Engine Design... the majority of its actions are NOT guided entirely by the PCM... but by its passive, non-electronic sensor based internal responsiveness to Changes in Oil Pressure. The cleaner and the thinner (within reason) the Engine Oil is... The Better the Cam Phaser can respond.

(2) 6,000 Miles of distance between one Oil Change and Another is a Long Road ... with No Turns in it and not keeping it around 3,000 Miles is a way to look for trouble with this engine for the same reason: The Screens in virtually every single Cam Phaser based engine with Higher Oil Mileage will probably have some amount of debris and Carbon contamination that would not have the chance to be in there with more frequent Oil Changes.

(3) Oil as "The Blood" inside of this Motor behaves is similar in a manner to Human Blood in that it is a multi-mixed liquid... with particles constantly being suspended in it. As such.... Motor Oil does more than just lubricate between moving metal components... its also serves to COOL them by transferring excess heat and it serves to CLEAN the spaces it moves through by picking up and carrying away particles of Dirt, Grit, Carbon, Engine Blow-By Gases and other products of incomplete combustion that will eventually clog up even the best filters on the market. Gasoline Vapors RUIN oil viscosity if left in there too long.

(4) Think about it... The Oil Filter you can hold in the palm of your hand is expected to clean and filtrate oil that moves through its insides for hours, weeks, days and months on end at temperatures of close to 200 Degrees Fahrenheit... and if left to its own devices... will back up enough to release the two bypass valves ...one in the block just above where it screws into the Engine Block...and the one exiting the Gerotor Pump. Under very hard acceleration ...a clogged oil filter can allow unfiltered, filthy oil to dance its merry way throughout the Oil Galleries and embed Metal, Sand and Dirt particles into the soft surfaces of the Babbitt Bearings of the Crank shaft and Camshaft and gradually grind their moving surfaces down.

 

[Redbeard]

If you would like to learn quite a bit about oil go to Bob's the oil guy. https://bobistheoilguy.com/putting-the-simple-back-into-viscosity/ It has been a while since I read his stuff in regards to oil, but the education is well worth your time. After reading you probably will never change to a higher viscosity oil again. And for the past 15 years or so I have sent most of my oils off to Blackstone for testing just to see how well the wear and tear of the engine has been. I know I will never go back to a higher viscosity oil and I live in Florida where the heat and not the low temps are the norm. And think of it this way, much of the wear on our engines is when it is started after sitting overnight and most of the oil is out of the crankshaft and away from the cams. The thinner oil stays in these tight spots much better so there is less of a "dry" start for the engine. My dodge ram with it's 4.7 requires 5w20 and it has been holding up fine the past 7 years.

 

[littleblazer]

The rotella T is a diesel variant isn't it? Thought there were issues with gasoline thinning out some of the diesel oils. If it's a gas variant you're fine and if not you still should be. Think it was only on direct injection. Only thing you're really hurting is an infinitely small amount of fuel economy. If you want to feel better about yourself fill a long vertical cylinder with 5w40 and another with 5w30. Weigh a marble and drop it in one and time how long it takes to reach the bottom. Repeat for the other. You can then calculate the viscosity of each at that given temperature. Guarantee they'll be about the same. Actually I bet the difference between the same one bottle to bottle will be about the same as well.

Edit: that's at room temperature.

 

[HARDTRAILZ]

I found lil different 5/30 10/30 5/40 10/40 with mine. I quit trying things though and stick with the 5/30 now.

 

[Capote]

@MRRSM oh no its not 6K per oil change, was saying that I did two 3k oil changes with that T6 Rotella, totalling 6K miles of that oil being used so far.

@littleblazer It's a diesel engine oil type

@HARDTRAILZ I tend to get paranoid sometimes, so I'll probably go back to 5w30 Castrol GTX High Mileage like I've always used or Mobil 1 after this. Rather have peace of mind and go back to the recomended weight.

 

[BrianF]

Most CJ4 oils also carry SN rating. Also the W rating in an oil is not its cold viscosity but more of a cold temperature flow rating. The lower the number the better it behaves as the temp drops. My only concern with running a thicker oil is how it would work with the VVT. But I must admit I have no information to back this concern.

I am looking at running a fleet oil next on my vehicles. Looking at a 5w30 CJ4/SN oil for my TB and my Cummins. Buy in 18-20 liter pails at a decent cost.

As well for viscosity. Some 30 weights are thick enough to be a thin 40 weight and some 40 weights are thin enough to be a thick 30. I always look at kinematic viscosity of the oils to see what I prefer.

 

[DocBrown]

I keep my vehicles until they have between 160k and 200k. I've experimented over the years with changing viscosity and oil types. I've come to several conclusions that really make things very simple.

1) There is no real advantage to changing from the manufacturer's recommendations for normal daily driving with modern engines. Modern being anything made since the late '90s.

2) Using expensive brand name oil is no better than using off-brand or store brand oil. I've yet to see an engine cease up using cheap oil. The key is what ever you buy needs to meet manufacturer's standards.

3) There really is a difference between dino based oil and synthetic. Egines run quieter with synthetic and it's also taken care of the dreaded tick in my 5.3. And to my point in #2, I've yet to pay more than $3.30 a quart for full synthetic oil.

4) Stay away from Fram filters. I had one disintegrate and nearly destroy the valve train of my '99 Catera.

5) The single most important thing you can do is change oil regularly, 3k, 5k, 7k, doesn't matter just so you do it. I just go by the DIC.

 

[littleblazer]

If it makes you feel better my uncle changes the oil once a year in his duramax and that is approaching 200k.

 

[Spanker]

Far too much talk about oil, and not enough about the filter. Get the most expensive oil you can find, and it won't do squat when paired with a cheap filter that blocks or internally separates after 50 miles.

It's the filter that gets the grit out of the oil. That grit will eat your front and rear crank seals, no matter how expensive your oil is. And also grind up the rest of the moving parts. Grit is not your friend.

ALWAYS use a premium filter. OEM filters are good...ACDelco, Motorcraft, Mopar, etc.

For those fanatics still changing at 3000 miles, try changing just your filter at 3,000 and changing the oil at 6,000. Stop living in the days (pre-1980?) when leaded fuel ash would block oil filters in short order.

And remember, "synthetic" oil IS dino oil. It's just refined a bit more and a contain a bit more additive. It is NOT a chemical substitute for conventional oil. Conventional and 'synthetic' oils come from the same hole in the ground.

If you must, for whatever reason, go for a cheap $20 oil change, at least bring your own PREMIUM filter. It's the best $5 you'll spend.

.

 

[Tiggerr]

Far too much talk about oil, and not enough about the filter. Get the most expensive oil you can find, and it won't do squat when paired with a cheap filter that blocks or internally separates after 50 miles.

It's the filter that gets the grit out of the oil. That grit will eat your front and rear crank seals, no matter how expensive your oil is. And also grind up the rest of the moving parts. Grit is not your friend.

ALWAYS use a premium filter. OEM filters are good...ACDelco, Motorcraft, Mopar, etc.

For those fanatics still changing at 3000 miles, try changing just your filter at 3,000 and changing the oil at 6,000. Stop living in the days (pre-1980?) when leaded fuel ash would block oil filters in short order.

And remember, "synthetic" oil IS dino oil. It's just refined a bit more and a contain a bit more additive. It is NOT a chemical substitute for conventional oil. Conventional and 'synthetic' oils come from the same hole in the ground.

If you must, for whatever reason, go for a cheap $20 oil change, at least bring your own PREMIUM filter. It's the best $5 you'll spend.

.

While I agree the filter is the most important thing... I use WIX filters pretty much exclusively...

Which is the mfg for the NAPA Gold filter line as well... for those that don't know that....same part numbers even except 1 number added by NAPA

I wholeheartedly and respectfully disagree with your take on oil...
Any major brand oil is pretty good oil these days..
I'm partial to Mobil, Castrol, or Valvoline.... to each their own

As far as synthetic oils go there are major differences in formulation...

My father a lifelong mechanic has been using Mobil1 since the early 80's with much success...

I've been wrenching all my life as well and been using it since the late 80's..also with great results.. anything low mileage or new gets Mobil1

I know many people who swear by Royal Purple as well...

When I used to race Mobil1 never let me down... it's also used by quite a few OEM's these days in high performance engines....BMW, Chevy, Dodge, Mercedes, Jaguar etc etc...

But my point was basically that buying anything just cause it's the most expensive is ridiculous... in anything... not just oil

 

[Mooseman]

For filters, OEM doesn't necessarily mean it's good. ACDelco, made by Champion, don't filter that well. I took apart a Mopar filter, which was exactly the same as a cheap brand filter. Video I made of it:

And this was an extensive test of filter media and construction comparison and you'll notice that ACDelco is no better than Fram.
http://www.gmtruckcentral.com/articles/oilfilterstudy.html

I use whatever good brand 5w30 synth that's on sale. Nowadays, you can't go wrong except for the Pennzoil natural gas stuff. For whatever reason, my truck would burn more oil than gas with it. Filter, I use Fram's ExtendedGuard that I usually pick up on sale.

 

[BrianF]

For synthetics, there is a difference.... kind of. the usual Mobil 1, Quaker State, Castrol, the older Pennzoil Platinum were all group 3 or so based oils. These are made from further refining group 2 base stocks, which are used for conventional oils. The higher end Amsoil line, Royal Purple etc use group 4 and 5 base stocks which are ester and PAO based. These are what people call true synthetics.

Unless you are running a bypass filter and very, very long change intervals, or track racing or cold starts in the arctic every day, our vehicles do not need any fancy boutique oil. Show me the used oil analysis that will provide empirical evidence of this.

I run one oil year round, I do many cold starts in the frigid Sask winters, sometimes without using a block heater. I also run them to about 24,000km. This is why I run synthetics. If I was in a milder climate I would not even bother.

As for filters..... Do a search of what the e-core is. Just because it says Mopar, AC Delco on it does not mean its good. But in saying this I doubt you will have any issues. Read up on the Purolators that were tearing in normal oil change indexes.

On my Tb and my departed Ram 1500 I ran Fram Ultras. Check out their filter efficiency and build quality. For the price show me a better made and efficient filter.

 

[Mooseman]

The XtendedGuard is basically the same as the Ultra. The efficiency of the filtering media is excellent in these. The bypass is basically the same as their cheapo lines but is actually sealed by a rubber gasket rather than on the cardboard end cap.

 

[littleblazer]

For synthetics, there is a difference.... kind of. the usual Mobil 1, Quaker State, Castrol, the older Pennzoil Platinum were all group 3 or so based oils. These are made from further refining group 2 base stocks, which are used for conventional oils. The higher end Amsoil line, Royal Purple etc use group 4 and 5 base stocks which are ester and PAO based. These are what people call true synthetics.

Unless you are running a bypass filter and very, very long change intervals, or track racing or cold starts in the arctic every day, our vehicles do not need any fancy boutique oil. Show me the used oil analysis that will provide empirical evidence of this.

I run one oil year round, I do many cold starts in the frigid Sask winters, sometimes without using a block heater. I also run them to about 24,000km. This is why I run synthetics. If I was in a milder climate I would not even bother.

As for filters..... Do a search of what the e-core is. Just because it says Mopar, AC Delco on it does not mean its good. But in saying this I doubt you will have any issues. Read up on the Purolators that were tearing in normal oil change indexes.

On my Tb and my departed Ram 1500 I ran Fram Ultras. Check out their filter efficiency and build quality. For the price show me a better made and efficient filter.

Most of Mobil 1 is PAO or group 4. The 5w-30 is rumored not to be a pure group 4 but the ep line and everything else is. There are some group threes in there as well but straight up Mobil 1 is PAO based. Amsoil base stocks more than likely come from Mobil as well. Everything else was solid.

 

[dkvasnicka]

Interesting read. I switched to Mobil 1 ESP 0W-40 just yesterday (oil change done after 4.300 miles). I did it because it seems my oil consumption went a bit up and also to calm down what I think are lifters.

The reason I went with 0W and not 5W is that the kinematic viscosity numbers for this Mobil 1 are very similar to the thickest 5W-30 oils. The thing with 5W-30 vs 5W-40 is that the common "5W" in there is far from "behaves the same when cold". I looked at many 5W-40 oils - thinking they will be the same when cold and just provide more cushion when hot - and the viscosity number seemed too high and I was worried about insufficient lubrication. Not that much with this Mobil.

One thing I'm worried about is that to make the oil's viscosity so wide-ranged a lot of complex additives are needed and they tend to break down faster, rendering the oil suboptimal sooner. Will keep and eye on it.

 

[BrianF]

Ya I dont recall what base stocks Mobil uses. I think their basic Mobil synthetic is group 3 now and the AFE and ESP use varying amounts of 3 and 4. I too heard that years ago the basic Mobil 1 was group 4. But I would have to really dig to find the facts. Regardless, Mobil is and always has been the gold standard oil. I like Pennzoil Platinum myself, mostly because I can get it for a decent price, much better than M1. I have some Castrol Edge (syntec) in it right now because it was relatively cheap on sale at Walmart and I happened to walk by and need it.

Group 3 base stocks have come a long way, to the point where they really are a non issue, especially on a stock, daily driven SUV. Hell any decent conventional oil these days is way more than sufficient. Group 3 should require less viscosity improvers/pour point depressants than group 2 and 4/5 should/could need even less than group 3. The base oil just behaves better the colder it gets. Amsoil has a heavy duty SAE 30 weight oil that also meets 10w30 specs. This is without VII, its just a by-product of really great base stock.

I would not think twice or lose any sleep over the possibility of a 0w or 5w oil shearing due to the use of VII. Will the oil shear? Possibly as some engines shear oil quicker than others. Will it cause any issues? Doubt it, especially in a stock engine/normal change index. As far as I can tell the 6 and 8 cyl engines used in this platform are easy on oil (if running correctly). Maybe 15 or more years ago there could have been shear issues with 5w and 0w oils but really they have come a long way.

I read a lot of used oil analysis on the Ford 6.0 diesel. Would shear a 40 weight oil, synthetic or conventional down to a 30 in no time. A 30 weight would stay in its weight steady. Guess what? No oil related issues because of this. Non issue.