As a nutritionist from the states, I have read tons of news regard to thr recycled cooking oil scandals in China over years, but this is actually the first time I tried it myself... Most restaurants in town may use some sort of Digouyou at different levels, usually the small ones will only the bad oil since it can make a huge saving for them. It's hard to taste out the Digouyou in food, but the reaction can be very obvious, the most common symptoms are diarrhea, stomachache and heart burn. Whenever you have above symptoms, make sure you have some meds or herbs with you, my experience is to drink water with 5 drops of oregano oil or garlic oil, do this every hour till the symptom is manageable. Usually it may take a whole day to recover from that cramps. If you still feel some kind stomach upset afterward, take some probiotics supplements (not sure if you can find in the local drugstore), at least twice a day, with a total dosage of 4-6 billion strains, and this will help your gut to recover from bad bacterial overgrowth. Try not to eat any food in any small restaurant, and if you have no choice sometimes (in a small town rather than Kunming) make sure you eat less oily food. BTW You can find safe, clean and delicious stuffs in Salvador, in case you can't find anywhere safe to eat. Good luck!

I am not a nutritionist, but had to do food hygiene courses. I am an expert in nothing.

If you get diarrhea then what the OP suggests as remedies will be useful. But the causes of being sick from chow houses are many, and oil is most probably not one of them.

The reaction from recyc are not obvious, in fact there probably is no reaction from the oil. Recycle oil is filtered oil. It will reach the same temperatures as fresh oil in cooking. Most bacteria cannot stand the tmps. All fried food places in the west will filter the oil at least once when it darkens. It is considered good management.

Gutter oil. One of the problems with gutter oil is that you cannot tell the difference between gutter oil and fresh oil in a laboratory. The gutter oil has been refined in same process and technology as bio deisel. If a lab cannot tell the difference, then what is the difference. Gutter oil, may be immoral but have yet to see any reports that it is harmful.

Some estimate that 10-20% of all cooking oil in china is recycled/gutter oil. the OPs supposition would mean that 10-20% of china's populations are sick most of the time.

BTW you can get safe food in many places in the city but you can get food poisoning anywhere.

I wouldn't trust fully trust any restaurant unless I see them harvesting or slaughtering the food and then proceed to clean and cook it. I mostly eat at foreign chains or places owned by foreigners, but in no way do I believe the food there is fully safe and clean. How many times do you think that meat has been refrozen and defrosted, are you certain that all the products aren't used past their expiration date? Every restaurant owner wants to make a profit.

There's nowhere cleaner and safer than cooking with your own oil at home.

Actually lab back in the states can tell the different between Digouyou and regular oil, because that early one is degraded by heat and bacterial. I have to address here that even after being processed by heat had filter, some becterials may still servive, like Clostridia Cdifficile which can tolerate very tough environment. Yeah I wish I can cook here...

I agree with all of you above. However I think it's worth looking at the whole place (and the kitchen) first. How they treat their food shows how they treat their guests.
Cleanliness (in my experience) doesn't have to mean safe food here.

Unless you take samples to analyze before you eat, there is no telling. Maybe just ask them what the price is for digouyou and if they use it :)

What is of more concern is: are there flies in the kitchen, don't eat uncooked food, are the vegetables washed (they do use human manure for fertilizer, and you sure know how many different illnesses and diseases, stomach problems and so on people can have), how do they keep the meat/fish? If fresh (except day-freah at the butcher) if not kept in a fridge (unless dried beef), you'll usually get stomach problems.
Just a couple things to keep in mind... :)

Wish I could upload a picture here. A couple weeks ago at a restaurant they had a cow sitting out in the parking lot, relaxed, munching away on corn... Unaware he was about to meet his end... That's called fresh :)

Actually, I have had to stop eating Nurou gan (dry beef). I got the shits every time I ate it.

I always assumed gutter oil contained heavy metals or other toxins in addition to other morphed toxins after the heating process..

Why not form a co-op lab to preform simple bacteria tests on local foods?

although gutter oil may be worse than most other oils, as far as i know all cooking oils in the supermarkets are unhealthy. olive oil is healthy but not that great when heated. butter is ok for frying, but expensive and not everything can be cooked in butter for taste. as far as i know, all other oils (sunflower, vegetable, peanut etc...) are unhealthy.

i use bacon fat. i buy the fattiest bacon in the supermarket, fry a couple of strips until the fat melts and use that for cooking.

coconut oil i believe is also healthy for cooking, but extremely expensive and hard to find in china.

Gutter oil just as good as regular cooking oil? I think not. I'm surprised nobody dug up the health effects on wikipedia:

"Gutter oil has been shown to be very toxic, able to cause diarrhea and abdominal pain. There are also reports that long-term consumption of the oil can lead to stomach and liver cancer as well as developmental disabilities in newborns and children.[10][11] Testing of some samples of gutter oil have revealed traces of Polycyclic aromatic hydrocarbon (PAH), a dangerous organic pollutant capable of causing cancer with long-term consumption. There is also potential for gutter oil to contain Aflatoxins, a naturally occurring mold.[7] Zeng Jing of the Guangdong Armed Police Hospital said about gutter oil "Animal and vegetable fat in refined waste oil will undergo rancidity, oxidation and decomposition after contamination, and produce toxic substances such as arsenic. It will cause indigestion, insomnia, liver discomfort and other symptoms"

There was a story in Sichuan about fake honey.

First, the man at the beefarm, mixed his honey with sugar to get better profits from "pure honey". Then the re-seller did the same. Then the distributor and whole-salesman did the same. Then the shop, where it was sold, did the same. The final product hardly had any honey left. But sold as the pure honey.

This goes for a lot of other products.

The basic philosophy these days is; why should I sell anything real when everyone else profits from fakes. Its out of control and taking place on all levels of production/selling.