Could this possibly be the oil pressure switch playing up? Just done mine, and ive gotta '98 Ph2 with 85k on the clock!
Easy way to tell (like mine) get under neath, look up the back of the block at about 2o'clock you should see the pressure switch, got one wire on it, and if its broken\on its way out (like mine) it will be leaking slightly...
Got one off ebay for £5 delivered! Change it out when you next do an oil change, takes 2secs to un-bolt and fit the new one. (infact u dont actually need to drain the oil, but would be less messy!).