My house has 2 types of window: Velux and double glazed units consisting of 2 panes separated by a 10cm air gap. in a wooden frame.
The Velux units have a label which advises that one should "lubricate the fittings twice a year". My first question is - what should they be lubricated with? 3 in 1 perhaps? I have never lubricated them in more than a decade but some are rather stiff to operate. The hinges seem OK it's the opening mechanism that is stiff.
The other double glazed units present another problem. Their hinges are very variable some stiff some loose. The latter mean that the windows cannot be placed in some opening positions they simply fall back. Two questions for these windows. 1) What lubricant to use on the hinges. 2) What is the correct way to adjust their tightness? The hinges consist of a sort of sandwich of several D-shaped pieces and 4 possible adjusters, 2 on each side! The outside of these windows can be cleaned by turning them over on their horizontal axes. Different D pieces seem to come into play when they are opened beyond approx. 90deg. A picture is worth a 1000 words and there are several on my web site at
TIA Frank