Ibought Mobil 1 5w-40 but the label also says Turbo Diesel Truck, recommended for 15W-40 applications.
It says API-SL on the label.
Is 5W-40 5W-40 or is this different from what we should use?

 

As I have said before, these oils are determined by the manufacturer because of the operating specifications of the seals, bearings, rings and such. Don't worry about what the bottle says about diesels. Yes, many diesels use that same oil.

As for the API-SL

API is an approval rating. No problem there.

The second two letters stand for the engine years that this oil had in mind. SL means for all engines currently in use (even old ones). SJ was the code for your car but thats ok because SL was made to be completely capatible with your year as well.

Here is a well written article explaining in better detail.

http://www.valvoline.com/carcare/art...=ccr20030901og