when my 98 3l gets hot 5m in to a drive i can smell oil burning had a look enderneath its looks like its driping on the the pipe at the back of the moter next hessian looking stuff raped around it but dosint look like its loseing oil

Hessian? Are you looking at the flex pipe? lol Rear rocker cover leaking onto the exhaust, probably.

rocker cover

That's just been done but

The shop didint tighting then fully?

checked the rocker cover bolts are tight?

Not yet how tight shod they be ? been a gaskit there don't won't to over tighting them

How tight should they be?

Not tight at all. Just done mine & the manual states just a few Nm (can't remember exacltly, but is was under 10Nm). Moderate finger pressure on the wrench should be all you need.

3-4 Nm. Pretty much finger tight, if you have strong fingers. lol If the mechanic has done them by feel, he may have overtightened them, and split the gasket. Pull the cover off and have a look. Or possibly there is a lump of old gasket still stuck on the head or cover. Have a look-see. If its a recent job take it back.