Oil Pressure LIght
 

My 2006 F4i has the correct amount of oil in it, but the oil pressure light sometimes comes on while I am waiting for the traffic light to change. It has done this on 3 occassions. When I rev the engine or starting riding the light goes off. The last two times that it occurred, I made a point of looking at my tach. On both occassions it was in the 1,100 to 2,000 rpm range. Any ideas as to the source of the problem?

what type and weight of oil

10w 40 but I'm not sure of the type. I had it changed at a shop while they were doing some other work. I just know that it is not synthetic.

Sounds to me like you are running oil that is too light and with the heat is losing enough viscosity to trigger the light while idleing. I would start with an oil change. If its thin enough to trigger the light then it is thin enough to provide less protection to your tranny and engine. Rotella T synthetic in 5w-40 seams to be a big hit. I run it and like it.