I've been using Amsoil's 15w-15 synthetic HD diesel oil in my '92 for years with noticable improvements over dino oil. I just got a 2004.5 and saw only the 15w-40 discussed in the owners manual. I am considering switching to Amsoil's Series 3000 5w-30 synthetic HD diesel oil, which seems to meet the same requirements, to see if there are any additional benefits. (Faster circulation, less friction and other claims.) Would there be any warranty issues?

 

Depends on who you talk to. I use the 15W-40 it cost a little less

 

the owners manual states 15w40 conventional or 5w40 synthetic , but i know of many that use 10 w 30 or 0 w 40 in winter with no side effects...so far. As warrenty goes , if the oil causes the engine to fail it would have to be proven.....which would be a pain in the butt...lot easier to keep the customer happy than try to prove them at fault. A hand shake and a case of beer takes care of a lot of warrenty issues.

 

Noticed you're in Florida where it's hot. IMHO run the Amsoil 15w-40 year round. I live in TX and we have near same climate and that's what I used in my truck. No problems or complaints. I changed the oil and filter (Stratapore) every 7500 miles and fuel filter every 10k.

I completed a LOF at 3000 miles with factory stuff and then switched to Amsoil at 7500 miles.

Regarding faster circulation, less friction, etc. At 7500 miles, change the rear and frt ends, etc out to good synthetic like Valvoline, Mobil 1, Amsoil, or Redline. That's where you make your improvements.

FWIW, TRUCK IN SIGNATURE SOLD LAST FRIDAY!

 

Locomotion - it's really unlikely that you'll experience any oil related warranty claims. However, none of the amsoil products are API licensed/certified, so they technically do not meet the requirements. While they physically are great products, I think if you had an oil related warranty claim and were using non approved amsoil, you could have an issue. Amsoil does put CI-4 on their bottle, however they are only 'rated', not actually certified/licensed by the API.

 

Lightman, what brand of oil do you use?

 

Lightman runs Delvac 1 (Mobil 1 Truck & SUV) with bypass filtration, and oil analysis.

 

Thanks guys.
I have an Amsoil dealer helping with my racing activities so I have their stuff in all my vehicles, from engines to rear ends. But it's personal observations as well as feedback from my engine and differential builders that got me hooked on the stuff. My thoughts of using a thinner viscosity oil in my new diesel are a by-product of doing the same in my drag car. If it protects as well while being easier to pump, reducing windage even just a little bit, slightly better mileage and other claims, I'll use it if at all possible! I did see that thinner oils are more prevalent in newer vehicles and their recommended use extends into warmer climates. So if it definitely would hurt to use it in a Cummins, why not! Either way, 15w-40 or 5w-30, I plan on continuing to use Amsoil even if it isn't API licensed/certified. That seems to be the same situation as SFI safety certifications for race parts. One has to spend thousands to certify a product, then stamp and number them to keep track. But when you have 2 of the same, exact product laying next to each other, the decal/stamp on one doesn't make it better/stronger than the other one. Of course, legal issues are part of the situation also.