my '99 spec slr doesn't have a sump plate drain so for me it's off with the blue plate, filter off to drain (just over 4l). check the magnom magnetic filter for swarf (nil, same as back of blue plate)
refit plate/magnom/filter
4l mobil 1, crank for a couple of seconds, then fire up, idle, pressure gauge straight back up to normal 4
no leaks
works for me (so far)
jerry