Cleaning cooking oil

I take it you mean you need to clean the filters or is the oil getting past the filters and in to the unit proper. I usually use very hot water and soak the filters in that. In Australia I used to use an Amway product called Industroclean which worked very well but I dont think it made any more. I would think that any detergent (ie alkaline) would work if you soaked the filters in it. I may be going to a manufacturer in the next couple of weeks so i will ask them if I do. If you need to clean the unit rather than the filters then I would use a soft plastic knife as a scraper (so you dont scratch any stainless steel part). Do not use any carbon steel product (like scourers or steel wool on your stainless steel as they will defintely cause rust.)If you need to scour inside then use a Scotchbrite and use it in the same direction as the "grain" on the stainless steel. If it is painted then hot soapy water is probably your best bet.
The trick with selecting a canopy/rangehood is to look at what your one does wrong and buy one that looks like it will work differently. There are plenty available as Shunde is a manufactuing base for them so your choice should be varied.

If you are renting an apartment and don't have an ayi, ask your landlord. Otherwise ask your ayi to get whatever is necessary for it. Ours does it for us.

@Chinamonty.....

Thanks for the tips. I am talking about the "filters". I use quotes because mine are sheet metal, not fibers. I soak them in a mix of hot water and some oil cleaning detergent I buy at the supermarket. It seems to work ok, but it takes a long time and several dunkings.

@cheeky.....

We own, don't rent. And unfortunately no ayi yet. If you can recommend one who has time and is extremely trustworthy, I would really appreciate it.

There are special sprays for cleaning exhaust fans. I have seen them in Carrefour in Beijing but I am not sure about Zhuhai as I have only lived here for 2 months. I can't tell you the brand but they have a picture of the fans on the bottle. The best would be to take a Chinese friend with you shopping and ask the staff. Jusco, Vanguard or Carrefour as the places to look for such things.
Getting a good ayi tip: if your friends have an ayi working for them for some time and they are happy with her, ask them to ask her if she has any friend as good as her willing to work for a foreign family. Mine doesnt, sorry. If I hear anything, I'll PM you :o)

A further thought on this. I saw a hand steam cleaner on TV recently. That would most likely be excellent for cleaning the filters.

one of the easiest solution is "don't cook". It never been a problem for me as I only make boiled eggs. ;-)

I have been waiting for that last piece of advice.