On my 1500 I saw the level is low, Can I buy some and fill it to the level shown at the side? So ill not go to mechanic?And what is your recommendation? Note: This is my Ram 1500 truck. 

Most of the coolant available at auto parts stores is compatible.   Get something with "Dex-Cool" on the bottle and it's "OAT" coolant.   There are different types of coolant but "OAT" is most common.  "OAT" stands or organic acid technology.  

 

Once again, any coolant labeled "Dex-Cool" is OAT coolant.  Dex Cool is a GM specification but is on most labels for compatible coolant.  This is not the same coolant that caused all the dex cool nightmares a few decades ago.  

 

 

Added: It's normal to have to add a little coolant to a turbo charged engine occasionally.  The turbo gets super hot, especially when you work the engine hard.  When you shut the engine off right after working it the coolant will get super hot in the turbo and boil.  This is what causes the "normal" coolant loss.   It's best to let a turbo charged engine (especially a diesel) idle for 3 to 5 minutes before shutting it off.  A few turbo charged engines have pumps that continue to circulate coolant for a few minutes after a hot shut down.  I'm pretty sure your Ram doesn't have one.  

Yes, add some coolant to the fill line. When was the last time the coolant was changed? I change the engine thermostat every 60K miles or so and the coolant gets changed as well. Last time I checked my coolant fill, it was way lower than expected and found crack in the coolant line flange that had to be replaced.

The truck is going to be 60000 miles soon, I don't know when they change coolant, Last year when I get very high bill from dealer, I decided to do everything by myself or a trusted local diesel mechanic, And I was doing good with oil changes and wheels but now I notice the coolant and I wanted to know if I can add some or better to bring to mechanic to change it.