Respected Sir. I would like to request you to please forget about giving your grandson a diagnosis, atleast for now. Autism
is quickly becoming a sort of "fashionable" diagnosis among the upper middle class people. I would like to know why you believe that he has Autism and supposing he does, I am sure you have already searched on the internet and consulted many others and already learnt that Autism as of now has no definitive treatment. From what I could gather from your question, he does appear to have mild delays in certain areas of development which I think will improve if given adequate training in that area. Also it would be advisable to keep monitoring his IQ and also identify other deficits as he grows up so that they can be caught early and managed accordingly. I would advise you to be in touch with a Pediatrician
for regular followup of your grandson.