Intermitent Starting Problem

Hello All

I am new to the forum, and this is my very first post, I think what I am about to ask has probably been asked before, but I cannot seem to find a diffinitive answer.

Anyway the problem is on the wife's run around Fiesta 1.4 TDCI 04. I seem to get this intermitent issue with the starter motor, for some reason, sometimes the SM will engage and turn the engine, twice and then disengage, sometimes once, then the next attempt its fine, sometimes 3-5 times then it will go etc etc, there doesnt seem to be any pattern to this. when the car runs it absolutely fine, great for getting about in the city. I dont think the issue is with the glow plugs, as the problem persists no matter what the temperature of the car. I havent checked relays, contacts etc as of yet. However I did read something about coolant temp sensors, and something about some kind of ecu software update, is there any truth to this ??? One other question, The oil light on the dash board stays on, when all other light go out before the car is started, but the goes out once the car is running, is this normal, or an early indication of oil level/pressure problems. Thans so much in advance, would greatly appreciate your input

Thanks

David