This lens has the coupling to allow for full-aperture metering on the Pentax spotmatic F, ES, and ESII.
The aperture is a bit slow to respond on this lens, but there is no oil on blades.
Should be easy to fix, or if you use stop-down metering it means nothing at all.
I just got one of these of my own two weeks ago. They are very sharp even wide open and make great darkroom prints (scanning does not do this lens justice), plus it's a desirable focal length both for 35mm and on APS-C digital cameras. Here's a snapshot I took when i got it, on a Canon 40D @f/3.5.