What 5W-30 oil brand are you using for the 6.6L gas?

[customboss]

Mannish Patel will

lead this. Worked with him at Cummins. Solid former BP chemist worth asking questions of. He’s now at XOM. 

https://lng.omeclk.com/portal/wts/uc%5EcnBDg4faq0jyjoj-coyDNf

 

 

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Edited August 12, 2025 by customboss

[Another JR]

22 hours ago, Black02Silverado said:

Don't know how I missed this, but to me it's a step sideways for the most part.

Thanks for the follow up. 

[Chuck FB]

I read through this thread some months ago and read it again to refresh myself. I have few miles on my truck as in around 3500 total now and since I have ran Mobil products for years ( delvac for diesels, synthetic gear oils for trucks and farm equipment ) I decided to try Mobil 5W-30 Truck and SUV which admittedly sounds very gimmicky from a marketing stand point and for what its worth Lake Speed Junior gives a nod of approval to it. However I also plan to run Mobil 0W-30 for the winter which they refer to in their lineup of "advance fuel economy" oils. Either oil should work fine all year around in theory where I live but there is an edge for flow for the 0W-30 by pour point as I have not been able to find the proper specs for a cold cranking rating on their website. My plan is to change the oil every 3000 miles although the longest I have gone on the oll so far is this second change as I was dumping it very early a couple of times to get rid of wear metals and take a peek at the filter each time. There is no science to what I am doing, just try to keep on top of changing it often vs pretending GM's so called normal oil change period is perfection. Costco here in Alberta doesn't have Mobil, they stock Castrol and Kirkland oil. 

[Grumpy Bear]

2 hours ago, Chuck FB said:

I read through this thread some months ago and read it again to refresh myself. I have few miles on my truck as in around 3500 total now and since I have ran Mobil products for years ( delvac for diesels, synthetic gear oils for trucks and farm equipment ) I decided to try Mobil 5W-30 Truck and SUV which admittedly sounds very gimmicky from a marketing stand point and for what its worth Lake Speed Junior gives a nod of approval to it. However I also plan to run Mobil 0W-30 for the winter which they refer to in their lineup of "advance fuel economy" oils. Either oil should work fine all year around in theory where I live but there is an edge for flow for the 0W-30 by pour point as I have not been able to find the proper specs for a cold cranking rating on their website. My plan is to change the oil every 3000 miles although the longest I have gone on the oll so far is this second change as I was dumping it very early a couple of times to get rid of wear metals and take a peek at the filter each time. There is no science to what I am doing, just try to keep on top of changing it often vs pretending GM's so called normal oil change period is perfection. Costco here in Alberta doesn't have Mobil, they stock Castrol and Kirkland oil. 

 

Viscosity, Lubricity, Solvency, Thermal Conductivity/Capacity. This short list are made on the base oil. A few can be mimicked with additives.

 

Issues of  heat rejection cured by the use of PAO's cannot be mimicked by any Group III/III+.

Solvency can only be solved with a co-base with superior aniline point. Esters are primary, Polyol Esters exemplary, some AN's workable and these without giving away something important. Additions of Group I or Group II fluids assist solvency but give away oxidation resistance. Stuff enough ZDDP and acid neutralizers in it and you can mimic solvency...for a while.  

 

The government is pushing lower viscosity damn the wear. Removing ZDDP and Calcium damn the wear and even giants in the industry are bending to that will....Even Mobil. Mobil is using the lightest Group III fluids it can with an VII polymer that has significant temporary shear losses. It hasn't any real 'natural dispersity' (solvency) and runs the minimum ZDDP/ZDTP and acid neutral packages. The get some features back with Borated Esters, moly, titanium and so on but they are sacrificial and heat sensitive. 

 

In other words the things that make for a great oil are deemed either to expensive or unnecessary 'upgrades'. Mobil, a Walmart shelf oil likes a profit. A big fat profit driven by big fat margins. That said...its sill workable if you can pinpoint a safe OCI length in the service you plan to give it. 3K sounds like a starting point. A generous one but a starting point nonetheless. Trust, but verify. Labs and reasonable condemnation limits. They will try to talk you into giving up on the oil only if the TBN hits 1. Try 50-60% of new. Not the publish spec but the VOA you will run as your baseline. The published number is a different test, with a different acid. 

 

 

[Chuck FB]

4 hours ago, Grumpy Bear said:

 

Viscosity, Lubricity, Solvency, Thermal Conductivity/Capacity. This short list are made on the base oil. A few can be mimicked with additives.

 

Issues of  heat rejection cured by the use of PAO's cannot be mimicked by any Group III/III+.

Solvency can only be solved with a co-base with superior aniline point. Esters are primary, Polyol Esters exemplary, some AN's workable and these without giving away something important. Additions of Group I or Group II fluids assist solvency but give away oxidation resistance. Stuff enough ZDDP and acid neutralizers in it and you can mimic solvency...for a while.  

 

The government is pushing lower viscosity damn the wear. Removing ZDDP and Calcium damn the wear and even giants in the industry are bending to that will....Even Mobil. Mobil is using the lightest Group III fluids it can with an VII polymer that has significant temporary shear losses. It hasn't any real 'natural dispersity' (solvency) and runs the minimum ZDDP/ZDTP and acid neutral packages. The get some features back with Borated Esters, moly, titanium and so on but they are sacrificial and heat sensitive. 

 

In other words the things that make for a great oil are deemed either to expensive or unnecessary 'upgrades'. Mobil, a Walmart shelf oil likes a profit. A big fat profit driven by big fat margins. That said...its sill workable if you can pinpoint a safe OCI length in the service you plan to give it. 3K sounds like a starting point. A generous one but a starting point nonetheless. Trust, but verify. Labs and reasonable condemnation limits. They will try to talk you into giving up on the oil only if the TBN hits 1. Try 50-60% of new. Not the publish spec but the VOA you will run as your baseline. The published number is a different test, with a different acid. 

 

 

I agree that these low viscosity oils are more than likely being pushed for the wrong reasons in gaining fuel economy at the possible expense of the engines life and so operating environment of the oil ( ambient temps ) as well as how loaded the engines application is and if its a turbo gas vs not would all factor into the outcome of the engines wear. 

 

The proof in what works best comes down to oil testing and that like you say is if the lab does the proper tests and isn't trying to con the customer into running the oil longer than what is best for the engines life, as well as actual engine tear downs to examine not only wear but sludge and corrosive factors. Obviously the average person isn't doing any of those things as there would be a lot of vehicle owners out there that have never changed oil in their life, its left up to a shop to do all the maintenance on their vehicle. I will say though that no matter what oil is being used, if there is an issue with direct fuel injection having excess fuel dilution in cold weather operating conditions it comes down to changing the oil more often unfortunately or so it would seem, same for diesels that seem to have inherent diesel dilution issues in certain operating conditions, shorter drain intervals.  

 

I've watched some of the videos and the oil test results from Demon Works ( A GM mechanic who lives in Utah ) on his personal 3.0 GM diesel and he is still in the process of testing various oils but it was interesting to see the testing of various 0W-20 oils be fairly similar in wear metals and then he ran a diesel specific 5W-30 and wear metals dropped in half, while that was only one test so far it was an indicator that for that engine type its probably not the best for its life to be running a 0W-20 during the hot summers and his trips to Vegas etc pulling an enclosed trailer. 

 

I wish I had easier access to some of these oils out there that would have better chemistry than the "usual suspects" easily obtainable through various stores but that just isn't the case where I am it seems and even if it was the price would be so far out I expect, its already crazy for any of the typical Dexos 1 oils at their regular price, probably the best price ( not sure of the oil itself though ) is the kirkland oil. The Mobil Truck and Suv oil is currently 57.00 plus tax for a 5 us quart jug regular price as it seems to keep creeping up in price like everything else just in the last few months as Canada circles the drain due to scum bag government dragging us into the toilet on purpose, and here we are sitting on the oil !. 

[diyer2]

If it was my truck and you plan on keeping it longer than most do,

https://www.amsoil.com/p/amsoil-oe-5w-30-100-synthetic-motor-oil-oef/

[Pryme]

3 hours ago, Chuck FB said:

I agree that these low viscosity oils are more than likely being pushed for the wrong reasons in gaining fuel economy at the possible expense of the engines life and so operating environment of the oil ( ambient temps ) as well as how loaded the engines application is and if its a turbo gas vs not would all factor into the outcome of the engines wear. 

 

The proof in what works best comes down to oil testing and that like you say is if the lab does the proper tests and isn't trying to con the customer into running the oil longer than what is best for the engines life, as well as actual engine tear downs to examine not only wear but sludge and corrosive factors. Obviously the average person isn't doing any of those things as there would be a lot of vehicle owners out there that have never changed oil in their life, its left up to a shop to do all the maintenance on their vehicle. I will say though that no matter what oil is being used, if there is an issue with direct fuel injection having excess fuel dilution in cold weather operating conditions it comes down to changing the oil more often unfortunately or so it would seem, same for diesels that seem to have inherent diesel dilution issues in certain operating conditions, shorter drain intervals.  

 

I've watched some of the videos and the oil test results from Demon Works ( A GM mechanic who lives in Utah ) on his personal 3.0 GM diesel and he is still in the process of testing various oils but it was interesting to see the testing of various 0W-20 oils be fairly similar in wear metals and then he ran a diesel specific 5W-30 and wear metals dropped in half, while that was only one test so far it was an indicator that for that engine type its probably not the best for its life to be running a 0W-20 during the hot summers and his trips to Vegas etc pulling an enclosed trailer. 

 

I wish I had easier access to some of these oils out there that would have better chemistry than the "usual suspects" easily obtainable through various stores but that just isn't the case where I am it seems and even if it was the price would be so far out I expect, its already crazy for any of the typical Dexos 1 oils at their regular price, probably the best price ( not sure of the oil itself though ) is the kirkland oil. The Mobil Truck and Suv oil is currently 57.00 plus tax for a 5 us quart jug regular price as it seems to keep creeping up in price like everything else just in the last few months as Canada circles the drain due to scum bag government dragging us into the toilet on purpose, and here we are sitting on the oil !. 

I believe the Kirkland oil, like the Walmart synthetic, are made by Warren oil and they perform very well. I run them without issue. 
 

mobil used to always be 24/5qts at Walmart (only thing I buy at Walmart is oil and filters and maybe fishing stuff) but they had consistently been pricing it at close to $30. I was there yesterday getting oil and they were actually dropped down to 24 and change but I still just got the Walmart oil. Which is 18/5qts. 
 

I also picked up the new top of the line fram endurance filter. It appears to be extremely well built. 

[Pryme]

1 hour ago, diyer2 said:

If it was my truck and you plan on keeping it longer than most do,

https://www.amsoil.com/p/amsoil-oe-5w-30-100-synthetic-motor-oil-oef/

Amsoil is in my trucks rear diff and I run it in my bike and atv. Good stuff. 

[KARNUT]

At almost 70 I lean on valvoline quick lube and the dealer for oil changes. I still do easy stuff like cabin filters and even some transmission fluid changes. I have an electric extractor. I’ve seen and read all the filter reviews. I’m comfortable doing 5K oil changes no matter what oil. With multiple vehicles it’s once or twice a year. I use the dealer because of their check sheet. I verify by watching. Just on a whim I just looked up who makes Hondas oil filters. Fram!? I can’t tell you how many bad articles I’ve read about Fram. And at Hondas change intervals. Interesting.

[Grumpy Bear]

6 hours ago, Chuck FB said:

I've watched some of the videos and the oil test results from Demon Works ( A GM mechanic who lives in Utah ) on his personal 3.0 GM diesel and he is still in the process of testing various oils but it was interesting to see the testing of various 0W-20 oils be fairly similar in wear metals and then he ran a diesel specific 5W-30 and wear metals dropped in half, while that was only one test so far it was an indicator that for that engine type its probably not the best for its life to be running a 0W-20 during the hot summers and his trips to Vegas etc pulling an enclosed trailer. 

 

Access is of course crucial. And when we don't have access then we do better with what we do have access to. Vis up is a perfect example and counter to GDI. Do you have access at whatever your version of Walmart is around you to Mobil 1 or Castrol 0W40 or 5W40 EURO spec? Don't believe Kirkland yet sells a Euro spec oil. 

 

In bold above I came to the same result. 

[Chuck FB]

3 hours ago, diyer2 said:

If it was my truck and you plan on keeping it longer than most do,

https://www.amsoil.com/p/amsoil-oe-5w-30-100-synthetic-motor-oil-oef/

I notice a very few select Amsoil oils being sold at automotive parts stores or Canadian Tire for example but typically not the more common viscosity engine oils for vehicles. I will freely admit that a couple of items keeps me from going down the road of Amsoil for use in engines, one being that for this GM requiring a licensed Dexos oil for warranty and while I can't claim to know the price of this specific Amsoil the theme has been through retailers that handle the brand, the Amsoil is insanely priced. The other factor is that I would have to chase someone down to find the oil and also I am one that doesn't like their marketing theme. I don't take issue with their oils, its the price and marketing method to get it into my hands that turns me away ( I am doing my best to hold my tongue over issues I saw and dealt with over the years, even with family that were into that type of sales ... ). But anyway don't take any offence to my comments here, I guess they are indeed my "issues" LOL.  

 

Oh and on a more scientific level as per looking at lab results from oil samples that have been done by various individuals in comparing a variety of oils in one particular vehicle of the same viscosity spec, the wear metals results were not standing out as lower but in some cases statistically higher vs some brands of oil and that didn't really help their hype in an instance like that. 

[Chuck FB]

7 hours ago, Pryme said:

I believe the Kirkland oil, like the Walmart synthetic, are made by Warren oil and they perform very well. I run them without issue. 
 

mobil used to always be 24/5qts at Walmart (only thing I buy at Walmart is oil and filters and maybe fishing stuff) but they had consistently been pricing it at close to $30. I was there yesterday getting oil and they were actually dropped down to 24 and change but I still just got the Walmart oil. Which is 18/5qts. 
 

I also picked up the new top of the line fram endurance filter. It appears to be extremely well built. 

That is what I have at least read as well as to the Kirkland brand being manufactured by Warren oil. A little while back Lake Speed J did a test and I can't recall if that was an engine test or a lab derived test on Walmart synthetic and another name brand oil ... I would have to go back to see what brand was being compared but the results between those two oils and the type of test performed did not put the Walmart oil in a bad light at all. 

 

As to the cost to you in the states at Walmart, that in today's world is one inexpensive oil change considering the volume of oil the L8T holds ( which is similar to the half tons these days ) , so 29.00 for oil and the cost of the filter. At a price point like that it doesn't make one feel bad to change the oil more often than if one was running an expensive oil and felt compelled to run it much longer just to justify itself. 

 

Forgive me if I still cringe at the name Fram but I do realize they make certain filter models much differently than the basic filter they have had around for years with the cardboard ends. That type of filter I would not knowingly put on anything of importance and my worry would be winter time with the extremely thick oil as even with the bypass the oil pressure may build up higher in the filter ( which is a good question, never seen an extreme cold filter test done ). For the fun of it I looked up my truck on the Canadian Tire website as they sell filters and probably because the L8T takes the same filter the half tons and the L5P duramax takes, its a popular filter. They handle a lot of Fram filters along with some other brands but in the Fram line they only have the Ultra Synthetic XG10575 assuming that is the same as the filter you have bought ? and its priced at 16.00 which ends up being similar if not more to the price I pay at GM for a Delco filter. 

Edited September 17, 2025 by Chuck FB

[Chuck FB]

5 hours ago, KARNUT said:

At almost 70 I lean on valvoline quick lube and the dealer for oil changes. I still do easy stuff like cabin filters and even some transmission fluid changes. I have an electric extractor. I’ve seen and read all the filter reviews. I’m comfortable doing 5K oil changes no matter what oil. With multiple vehicles it’s once or twice a year. I use the dealer because of their check sheet. I verify by watching. Just on a whim I just looked up who makes Hondas oil filters. Fram!? I can’t tell you how many bad articles I’ve read about Fram. And at Hondas change intervals. Interesting.

Getting old is great isn't it ... I am not quite your age yet but I probably move like I am older, sure feel old anyway. I don't blame you at all for getting your oil changed somewhere and it sounds like where your going your able to see what is going on and what is getting done which really surprises me. 

 

Oh I am sure Fram is capable of making decent filters, its that they also know how to make the cheapest filter out there I assume to capture the economy market. More than likely there are only so many filter manufactures out there and they would build filters for various companies to a certain requested spec. Which reminds me that Canadian Tire being a place that a lot of Canadians go into because its a store that has a lot of stuff ( tires is a fraction of it ) and they sell quite a few brands and types of engine oil but what filter do they sell ... Fram .. whole multi shelf isle taken up with Fram filters. They also sell to a lesser volume a few other brands and I will call it there house brand ( they also sell their house brand of engine oil as well ) . 

[KARNUT]

19 minutes ago, Chuck FB said:

Getting old is great isn't it ... I am not quite your age yet but I probably move like I am older, sure feel old anyway. I don't blame you at all for getting your oil changed somewhere and it sounds like where your going your able to see what is going on and what is getting done which really surprises me. 

 

Oh I am sure Fram is capable of making decent filters, its that they also know how to make the cheapest filter out there I assume to capture the economy market. More than likely there are only so many filter manufactures out there and they would build filters for various companies to a certain requested spec. Which reminds me that Canadian Tire being a place that a lot of Canadians go into because its a store that has a lot of stuff ( tires is a fraction of it ) and they sell quite a few brands and types of engine oil but what filter do they sell ... Fram .. whole multi shelf isle taken up with Fram filters. They also sell to a lesser volume a few other brands and I will call it there house brand ( they also sell their house brand of engine oil as well ) . 

There’s a lot made about oil and filters. Working with my family business I’ve owned many vehicles and equipment. It’s in the hundreds. Two hundred myself. We’ve even had a salvage yard for awhile. My father thought it would be a good idea. Most vehicles we bought off the public were driven in. Couldn’t pass emissions and too costly to get them to pass. Iv had two failures in my lifetime. One drag racing. Spun a bearing still drove home. A Ram V-10 pulling a tractor cross country a factory defect replaced at the dealership for free. Usually the culprit is something other than oil for engine problems. It seems valvoline may have an answer with build up problems with restore and protect. It’s entertaining reading about people worrying about oil and filters. 

[Chuck FB]

5 hours ago, Grumpy Bear said:

 

Access is of course crucial. And when we don't have access then we do better with what we do have access to. Vis up is a perfect example and counter to GDI. Do you have access at whatever your version of Walmart is around you to Mobil 1 or Castrol 0W40 or 5W40 EURO spec? Don't believe Kirkland yet sells a Euro spec oil. 

 

In bold above I came to the same result. 

Yes, by testing like that which you have also done, that would point to vehicle manufactures having gone too far to the left of center to win on fuel economy and yet get past the warranty ( or not ) vs doing what's best for the mechanics of the engines health. I have to wonder if the transmission oil is now in that same theme with the ULV , no wonder there are so many "Tranny" issues these days ... 

 

For most of my life in buying oils I was buying oil through bulk suppliers who also sell fuel but ironically and yet not all that surprising, the bulk Mobil dealer handles little in the way of the vast confusing packaged oils that Mobil makes when it comes to ones like Truck/SUV, high mileage engine, high mileage oil, and on and on and on. I had a chat with one of the staff at the bulk supplier last year and he said himself that its an eye rolling experience to walk into a place like Canadian Tire or other store front retail stores that sell all the "flavours" of Mobil oil. He said they could probably get whatever I wanted special ordered in and at who knows what price but they mostly deal in large quantities of oils that fleets use for heavy diesel equipment or pickups etc. So going back to sourcing the various brands of oils such as Mobil, Valvoline, Pennzoil, Castrol, even Royal Purple and possibly Lucas, the stores that come to mind would be Canadian Tire but also Walmart as a couple of chain stores. Having said that I have not been past the oils section in Walmart for years as I rarely go into the store and looking it up online is a mess as most of what is listed shows it doesn't exist in Walmart and its sold through online and the prices are beyond insane. I would have to physically go to Walmart and see what they actually carry in the store and what their prices are on the shelf. 

 

Oh, I sort of flew past the actual point now which I gather was seeking out Euro spec oil which I presume then does not meet the Dexos label, but yet does meet the requirement to not self destruct a GDI engine ?. I've never figured that out in the last years, how any of that makes sense that there is a Europe spec that would protect GDI engines and yet somehow that isn't proper by GM specs to use in their engines so they had to create their own set of specs ?. So is it the "40" aspect of those oils that you have oil sample results on that are better than the 5W-30 spec that is the highest viscosity typically on the American market that covers the Dexos 1 theme ?, other than GM's own packaged 0W-40 which they throw at the 6.2 in an effort to hold those engines together longer. The 40 grade Euro oil does exist up here but would be handled in a lot more limited volume from what I have seen so far, again can't comment on Walmart until I meet the greeter