Ok ive done alot of searching regarding noisy tappets and i realise most peoples are only loud when the motor is cold.

Well when i start my motor on a cold morning the tappets are quiet and only start to become loud when driving for 15 or so minutes..does this sound like somethings wrong?

I just done a oil change, and flushed the old shell 20w50 and put in some penzoil 15w40 with some nulon lifterfree.

Also my oil pressure when hot is almost at zero when pulling up to traffic lights..

what do u think my problem is, and is there anything you can suggest which may resolve it?

definate oil presure issue, the tappets are loud as the oil is not getting up to them and they have bled out and are sitting in a compressed state.

This sounds stupid, have you got enough oil in there? the lifterfree stuff from memory is only ment to be in for a short time, do an oil change again, the penzoil should be fine, otherwise grab something like HPR 15 or 20, or a decent semi synthetic oil. IF your problems persist, I would start looking at oil pumps, oil pickups and stuff.

also caused by thin oil, oil gets thinner when hot also with the lifter free it would be getter thinner than normal

use some 20-50 oil or even slightly thicker to build some oil pressure. how old is the oil filter?

20/50 in an OHC motor? I think she's more than a little tired if you have to go that heavy to keep her quiet.

knock the tappet cover off to see if any dramas or just change ya oil (although flush it first) use some nulon lifter noise stuff and should fix it

if not oil pressure issues

well apparently the old owner (bought car 6 mnths ago..) was using 20w50 according to the invoices..

And yes i have added the lifter free and tune about 5 weeks ago, and also put in a brand new filter..