I changed out to Conoco hd diesel oil (was given to me). It wasn't bad at first, but about 20 miles, I thought I had a gear oil leaking.

 

i use shell rotella 15w40 in my dodge truck and tractor.

I think it's great oil for old dodge diesels.

i have never smelled anything odd, wife rides in truck all the time and believe me, if there was a bad smell, she would let you know.

do you buy that bio-diesel fuel??? could be that, maybe fuel filter needs changing?

you must have something else wrong with your truck, as the second brand of oil also smells bad.

just my humble opinion:

 

haha, aint that the truth. Some things are universal.

 

It's the engine oil. I got a whiff when I checked the stick this morning.

 

I've smelled it before, going from Fossle to Synthetic. And going back. But not in between when using the same oil.

On my 08, I went over to Rotella Synthetic at 30K, but didn't smell the change. I think that's because the crankcase doesn't vent to the atmospehere like the 12 and 24 valves do. Your tractor is probably a closed system too if it's 04 or newer. That's why you don't smell it. You're burning the smell