Any idea why my car blew up with these symptoms

Hi All,

I've got an Isuzu Trooper 3.0D Manual, 2001. It basically blew up yesterday. I was driving along in fourth, around 30 mph. Then all of a sudden the revs went to maximum and there was a very loud and rapid clicking noise. Even though I was in gear, the car was just free wheeling. I turned the engine off straight away but the revs were still maxed out for around 5 seconds. Rolled to a stop and there was a huge amount of blue smoke billowing out of the exhaust.

Towed it to a garage and the guy said that there was probably around 3 litres too much oil in the engine.

I had it serviced 2 months ago and haven;t even opened the bonnet since. There is no way anybody has put any extra oil in it. Could this oil have leaked in from another subsytem or something. Also would too much oil cause these symptoms. It was fine up until it went bang.

Any ideas would be appreciated,

Cheers