is it normal that sucks air in the rod measure oil
check your positive crankcase ventilation elbow...should rattle when you shake it..if not the crankcase will NOT vent properly~! https://www.google.com/?gws_rd=ssl#q=pcv+elbow
There should only be a slight vacuum, barely noticeable, if it is pulling a fair amount then check the crankcase breather, it maybe totally plugged. At least you know that the PCV valve is flowing.
Search Dodge Ram 1500 Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
Dodge Ram 1500 Experts