Can anyone help me with this please?

You get to 50 miles an hour and it starts surging,
what causes that? The Glowplug light keeps flashing on the dash. I'm not sure what to do at the moment :(

Also, does it matter what Engine Oil you use?

Thanks for any help!

Engine oil is important, I believe 5W30 is the required content (semi Synthetic?) check your manual to be sure.

As for the surging, it could be a number of things, fuel pressure perhaps due to fuel filter requiring replacement would be my first bet!

You need to see what fault codes it shows.

I took it to a garage to see if they could offer any advise, but they wouldn't plug it into the computer until it had stop working :)

They are idiots for not plugging it in codes are always there.. It's a long shout but my 1.8 diesel surged at about 50-60 turned out to be a split pipe an at that rev range was causing the pipe to reduce air flow and surge until the pipe stopped being sucked tightly sealed

lmfao "wont plug it in until its stopped working"... I have never heard such bull in my life.

Any mechanic, garage, or dealer who can charge money for plugging the car into a computer and doing a 30 second job and earning a few bob would do it, but refusing to plug it in? that is a new one!

anyway, error codes need to be checked as mentioned if you have the capacity to, its not an expensive thing to buy an adapter yourself if you can wait a few days for delivery.

Thanks for the help! I'll look intot these suggestions :)