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rileyc's Achievements


Enthusiast (2/11)



  1. I have always owned Chevy trucks, and I am looking to purchase a new one-ton gasoline powered pickup for hauling a truck camper. I have spent a lot of time researching all the major manufacturers: Ford, GM, and RAM. Each brand has some advantages as well as disadvantages in terms of technology, reliability, and performance. The new GM L8T 6.6L engine appears to have some early release issues which, hopefully, GM has/will correct. I like both the horsepower and available torque from this engine. I further like the simple, robust design of a cam-in-block truck engine, and I am glad GM did away with AFM for this engine. Regarding the 6L90 transmission, it's reliable, but both Ram and Ford offer 8 and 10 speed transmissions respectively in their one-ton trucks. To me, the 6L90 is outdated when compared to the competition. I do understand Ford has/is having some release issues with the 10R140 transmission which they are now working through the problems. Ram uses a ZF 8HP75-LCV which has a good track record, and RAM is a strong candidate for my business. Not only does GM need an updated transmission with the L8T engine, they need to offer a 4.10 rear axle as well. In my opinion, having a 10 speed transmission and the option of a 4.10 rear axle would help level the playing field. I like Chevy trucks; so, I am willing to wait to see if GM is going to make a 10 speed transmission available for the 2023 model year. If not, I may be buying my first non-GM heavy-duty truck.
  2. Given the history of the Duramax being easy on oil, I recommend using an API approved 15W40 conventional HDEO. Name brands or API approved store/private brands will do a good job in the Dmax. Personally, I watch for the oil rebates offered by the big three: Delvac, Rotella, and Delo. Currently, Mobil Delvac has killer rebates available through December 2019. For example Mobil Delvac 1300 Super 15W40 has a $6/gal rebate. Check out their promotions: https://mobiloil.com/en/promotion/mobil-promotions/40-off-mobil-delvac Make sure you check the list of approved retailers. Also, if in doubt about a certain retailer, call them. I can purchase Delvac 1300 Super 15W40 from an approved retailer on sale for $11.99/gal - $6.00/gal rebate = $5.99/gal cost after rebate. Hard to beat that price for a respectable HDEO.
  3. It's my understanding that Mobil Delvac 1300 Super 15W40 is the Duramax factory oil fill. Past formulations (e.g. CJ4, CI4+) of Mobil Delvac 1300 Super have performed very well based upon various Internet used oil analysis (UOA) postings and customer testimonials. Fast forward to today, and GM is using the current CK4/SN Mobil Delvac 1300 Super formulation as the factory fill in the Duramax. As many of you know, the CK4/SN formulation of Delvac 1300 Super is a reduced phosphorus (800 PPM) heavy-duty engine oil (HDEO) that Mobil designed as a universal oil for mixed fleet applications (diesel and gasoline engines). The reduction of phosphorus raises a question about wear protection. According to Mobil, the CK4/SN formulation provides a 20% improvement in wear protection over the previous CJ4 formulation and 50% more wear protection as required by API CK4 testing standards...which is good. However, I have yet to see any (UOA) postings of Mobil Delvac 1300 Super 15W40 CK/SN that confirms that the various metallic wear rates which verifies the new formulation is providing good wear protection. Again, my interest in UOA data for Delvac CK4/SN 15W40 is to make sure the reduction of phosphorus in the formulation has not compromised good wear protection. I, personally, have been using the previous formulations of Delvac 1300 Super 15W40 for many years with good success, but I would like to see some UOAs of the new Delvac CK4/SN formulation. I have checked the BITOG website, and there are not any Delvac 1300 Super 15W40 UOAs posted. Do any members here have any UOAs of Delvac CK4/SN that can be shared? On another note, the Duramax runs fine on API approved 15W40 conventional heavy-duty diesel oil. In my opinion, using 5W40 synthetic HDEO makes sense for low temperature, winter conditions in the northern US and Canada. And, for use in extended drain oil change intervals (OCIs) applications; however, most diesel owners dump synthetic oil far too early never capturing the long-drain value of synthetic oil.
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