ought to in questions

Hello! Will be obliged to get your expert opinion on the usage of ought to in questions and in the negative form. I know, that it is not frequently used, it’s formal, and can be easily replaced by should, but still…
What is bothering me, is that different sources give different information…
Oxford advanced learner’s dictionary on line gives the examples where in questions ought is followed by
to :

Ought I go to the party "?


I would say ‘ought’ should be followed by ‘to’ both in positive statements and questions as in: I ought to go there/Ought I to go there? In negative use the ‘to’ tends to disappear as in: You oughtn’t take more food than you need. This has come about because of the laziness of saying: I oughtn’t to go there.


Thank you very much for your answer, Alan!