I don't clean any top frame, i only clean anything that breaks up the glass i.e. if the window has got top openers i have to clean the part of the frame under it, & thoroughly too. Keep in mind i never & have never sold wfp on clean frames as i don't need to, i get perfect results just cleaning glass. If you've implanted the whole clean frames thing into a customers mind then it may be difficult to reverse this. I've never been requested to clean a frame in over 4 years wfp (only one trad), no customer has ever mentioned that the frames look dirty either & 9 times out of ten they don't look dirty but customers do like spotless glass
If i did get asked to clean the frames i would of course but at a premium cost.
To be able to work this way requires some specific techniques & equipment (nothing expensive) & some practice BUT perfect it & oxidized top frames are no longer a problem, niether are first cleans or dripping vents etc.
I will explain later if you are seriousley considering this method as a few tips/pointers make all the differense.
Tony