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I've been using Shell t6 5w-40 full synthetic oil . I'm thinking of changing to Delvac 1300 15w-40. The reason I want to change is never I've done some research on best motor oil and the delvac has some great reviews. The Shell T6 has snaptube vidmate been okay but seems not to last long when my oil change interval gets to 20 %. So just wanted to know y'all oil use and which one of these y'all would prefer?
 

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Both oils will do well in your engine. Not sure which engine version you have or what your climate is. The 5W-40 has a higher quality synthetic base stock. The thinner oil at startup may give you a slight advantage normally in building up oil pressure and a greater advantage when it is cold out. Both oils will have about the same thickness when hot. My personal preference would be the 5W-40.
 

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My 2020 Duramax asks for 15w 40 full synthetic, at my local auto parts store they only had rotella T6 in 5w 40. I bought 10 quarts of the 5w 40 and changed my oil, have I any need for concern because I did not run 15w40?
A lot of guys run 5W-40, it's not an issue. That being said, do yourself a favor and buy oil at Walmart and not the auto parts store, you'll save a good chunk of change and many Walmarts sell Rotella T6 15W-40.
 

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I've been using Shell t6 5w-40 full synthetic oil . I'm thinking of changing to Delvac 1300 15w-40. The reason I want to change is never I've done some research on best motor oil and the delvac has some great reviews. The Shell T6 has been okay but seems not to last long when my oil change interval gets to 20 %. So just wanted to know y'all oil use and which one of these y'all would prefer?
Many of these oils are developed by third party specialty additive companies, the largest of which is Lubrizol in Cleveland. They have extensive lab and dyno test facilities that conduct back to back testing on a wide range of oils from different manufacturers. FWIW I know a lot of truck companies that use Delvac and it is a fine oil, but I did ask Lubrizol "what is the best diesel oil", the guy I was dealing with called the head of development and got a resounding Shell Rotella T6. Bottom line is there are many good oils out there and given the relative light use most of our engines see all would be ok. Best advice I got was follow OEM guidelines for change intervals and use a quality oil filter(NOT FRAM) and all will be good. Personally I use OEM filters and T6 and change every 10K.
 

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Shell Rotella oils have been a favorite for diesels for many years.

Shell has several versions of Rotella available that are 15W-40.
(including a T6 15W-40 diesel oil; not all T6's are the same)

They now have versions for gasoline engines as well.
Their site has lots of info about the various versions including a new one for gasoline engines.

 

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anyone have any thoughts on using the T6 Arctic blend 0 - 40 in the winter months?
 

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I run theT-6 and get Blackstone oil samples every other change. I am currently going 25,000 miles between changes and have over 975,000 miles on my 2011. Blackstone keeps telling me to go farther between changes. The most I have went was 27,000 and it was still good to go farther according to them.
Have you owned since new? What all have you replaced in that amount of miles? Still running emissions on LML?
 

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I'm too picky for my own good and worry too much. I am trying to improve by just doing what the manual says and calling it good.
 

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anyone have any thoughts on using the T6 Arctic blend 0 - 40 in the winter months?
I have ran a 0w40 in my truck year round for 8 years. Its still a 40 wieght oil when at operating temp, but it starts flowing sooner then any other oil. There are no downsides to a 0w40. If anything, going from a 15, to a 5, to 0 improves flow during coldstarts.
 

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I have ran a 0w40 in my truck year round for 8 years. Its still a 40 wieght oil when at operating temp, but it starts flowing sooner then any other oil. There are no downsides to a 0w40. If anything, going from a 15, to a 5, to 0 improves flow during coldstarts.
Which 0W-40 are you using?
 

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Which 0W-40 are you using?
I have been using Mobil Delvac ESP 0w40 paired with a donaldson filter. It doesnt matter what brand unless you plan on sampling and pushing an oil to its full life potential. I have used 0w oils for over a decade in all my vehicles, from honda to chev. I sampled the mobil delvac when I first got the truck and started using it. Did samples when I changed the oil and Black stone said all looked good and could run it for longer, I never have ran it longer. That said, I dont panic when the DIC reads 0 since I know I can safely run longer, but I still change it frequently.

Im used to doing oil changes every 5,000km. Now I do them every 15-20,000km because thats how long the DIC lets me go, and thats how long Blackstone has told me I can safely go with another 10-11,000km possible (which I wont personally do). I never found Shell Rotella when I was looking for it, and I specifically wanted a 0w40 because I live in the north in Canuckland. Only reason I use what I use other then that was price and availability.
 

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I have traditionally understood that the viscosity at full operating temperatures for a 0W-40 oil vs a 5W-40 would be the same as would a 15W-40. I have noticed that according to various charts this is not always true. Here are a couple examples below. I have found this surprising. There is typically no difference in oil analysis like this for 5W-40 vs 15W-40. In this case below note that one is a new sample and one is used but I have seen this pattern before when both UOA samples are at the end of their use. Keeping a higher viscosity in my TDI Jetta made a huge difference in my wear numbers. Iron dropped by 50% when I started adding 1 quart of 20W-50 and 3 quarts 5W-40 mix. This gave me a slightly thicker combination. Obviously a different engine but I do think that film strength matters. The only way to know how this might perform in a Duramax would be to do some long trials with each. I am definitely feeling ok about using 5W-40 in my Duramax. I would want to find some UOAs using 0W-40 before adopting that. My guess is that it would be fine.

cST 100 Viscosity of 5W-40

cSt 100 Viscosity of 0W-40
 
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