I currently run rotella-t 15w-40 but I keep hearing more and more about this synthetic oil mobile 15w-50 I was wondering If anybody is running it and if so how do you like it. do you get better fuel mileage with it? how much better? are the oil change intervals longer? how much longer?

 

i cant say much about fuel mileage and change intervals with the mobil oil, but i work for a freghtliner dealer and mobil is the "factory" oil as far as freightliner is concerned. i can tell you that the sprinter that freightliner markets (soon to be dodge also) they only allow delo 400 syntech to be used. it is not a full synthetic oil, but its recomended change intervals for sprinters is 10,000miles. its the only oil i will use in my truck. it is however pricey, so if money is tight, the mobil oil is great! i would stay away from rotella....its bottom of the line generic oil with a fancy label. i have seen many trucks come through that use delo or mobil and have 900,000 plus miles on them with original motors. many of our in frame motor swaps are on trucks that get serviced at the truck stop and get rotella.

 

I don't believe the 15W50 is rated for diesels. You need an API rating of CH-4/SJ or higher. Mobil Delvac or Super 1300 are rated for diesels.

 

I only use Mobil Delvac 1300 in my truck. Every 2500 miles with a motorcraft 1997 filter. Will use nothing else then mobil delvac.

 

thank you for all the info guys