Loud ticking sound from engine

[tonymor]

My mk1 has developed a continuous ticking sound from the engine. I've known it on start up for a second or two but now it's louder and continuas.
Any ideas?

[tonymor]

Thanks it's running on that very oil at present.

[tonymor]

I'm thankful for all the advice on the thread
I'm delighted to say that warming the engine and then applying the wynns has made it as sweet as you could ever wish for .