A couple months ago i bought a 2004 5.9 with 80,000 miles on it. every so often when i get one running it or while im using it no matter towing or not highway or city i smell warm oil. Its not a burnt oil smell but the smell of warm oil. I work in a diesel shop working on equipment all day and dont exeriance this happening with them thats why i find it odd on my truck. im beginning to think i might have excessive blow by and what im smelling is excessive crank case gases coming out the case vent. my other reason is when i change the oil it tends to blacken quick. ive changed diesel oil before so i know it turns black fast but the way my oil is it seems to me to be too black. im wondering if anyone on here might have some other ideas, or maybe the blow by spec for this truck so that i can test it.

Thanks

 

you are using valvoline premium blue 15w-40, heavy duty diesel, arent you . that is cummins factory fill. i have been using it in my dakota V-6 3.9, for 3 years NO trouble. AT LEAST use a diesel oil. just my idea. all so check the PCV, it is very important to keep the moisture out. course you know moisture is needed to make acids, in crankcase.

 

Did you use Rotella aka Rosesmella many say they get a odd smell when using Rotella oil for the first thousand miles or so.

As for getting black so fast its from the 3rd injection event and EPA mandated smog changes on 3 Gen engines.