Originally Posted By: armyn21
Im planning to do a OCI @ 7500miles on AMSOIL 15w40 HD DIESEL and MARINE OIL.. we use to put rotella T6 5w40 and do 5000 miles on it. and we drive it around 700 miles a week with a payload of around 5k lbs bec of our recyling business.
1) Welcome to the site
2) At the risk of being blunt, your maintenance plan is a total waste of money
Running synthetic for "normal" OCIs will net you no benefit in protection, and will cost you dearly to purchase, typically on a ratio of 3:1.
If you want to get your ROI on the synthetic, then you'll have to greatly extend your OCI, at least to a minimum of the cost factor. I often come off as "anti-synthetic" but that is simply not true. I am "anti-waste". Any person can over or under utilize any product. The "best" oil is the one that fits your maintenance plan and gives good protection, for the least cost. This is not a game to see which oil can give the lowest wear, but a tool which you can use to maximize your investments. Synthetics are great tools, but ONLY if you understand their benefits and limitations. That goes for ALL products.
Further, the myth that CI-4+ is somehow "better" than CJ-4 is unfounded. The reality is that when using ULSD, the CJ-4 performs VERY admirably, and can show benefits in wear reduction over the predecessor, as proven by the major oil makers (Shell, Chevron, Mobil, Castrol) and our own used oil analysis.
Review our long history of used oil analysis on this site, and you'll see what I mean. Your engine is a good one and there is every reason to believe that typical use (even hard use) can easily be survived by conventional 15w40 in your area. I recall a used oil analysis of a Cummins this year where a guy is going 15k+ miles on conventional Valvoline Premium Blue! Here are but a few examples ...
Conventional oil:
https://bobistheoilguy.com/forums/threads/2007-dodge-ram-5-9-oil-analysis-questions.149156/
RL syn:
https://bobistheoilguy.com/forums/threads/04-cummins-5-9-crd-red-line-15w40-diesel-7-500-mi.152715/
Schaeffers syn:
https://bobistheoilguy.com/forums/threads/2004-5-cummins-22536-miles-on-5w40-schaeffers.152294/
My point is this:
You can EASILY run 7.5k miles on conventional oil in your engine and get the same wear protection as any synthetic. Any off-the-shelf CJ-4 oil will do the job for 3x less money than the Amsoil (or any other syn), given your maintenance plan and described use factor.
Again, welcome to the site, and I appologize for the dose of harsh reality, but I presume you came here for advise, and we owe it to you and others to offer the truth. But don't take my word for it; review the hundreds of used oil analysis and make up your own mind. The data speaks for itself.
Read my signature line, and you'll get the idea ...