Had engine replace in my 1996 Isuzu Hombre in April 2009 and have had regular oil changes since. In the last month I have started having the truck show that my oil is low after I have driven say 35 to 50 miles (highway) and when I stop the truck sounds like a thrashing machine,which I figure may be the lifters but when I check the oil it shows that I am fine on oil and the oil is not burned or anything so my question is I was told that I may need to replace some kind of oil/fuel sensor,is this what I need and if so what exacatly called.
shows low oil after driving on 1996 Isuzu Hombre
The issue you describe is caused by a faulty oil sending unit. You can change it yourself very easily. It can be purchased online for as little as $10, and generally, the auto parts stores charge around $30.
I know of no oil/fuel sensor. Clearly a new or rebuilt engine should run perfectly for many, many miles, take it back to the shop that put in the engine, it is their problem.