On my Shadow II I've noticed the oil pressure barely gets up to the white area, varying around the dark area below, even on high revs. On tickover it's almost at zero. The oil pressure warning light hasn't come on. It's nicely full of oil. Is this a worry? I'm sure it used to be in the white. I had a filter and oil change a few years back but have done only a couple of thousand miles since. Regrettably it spends quite a bit of time, especially in the winter, sat in the garage. I don't know if that could have anything to do with it. Any advice very welcome.