The real question here is not so much what are the components of the medication but rather whether or not it has a good taste.
If it has no taste, it doesn't require a blessing at all. We only say blessings on food that have good taste (ha'naat grono, pleasure of the throat) or nutritional value (water has no taste but we still enjoy it when thirsty).
If the medication has a good taste, then we say sheakol according to many opinions (R Shlomon Zalman Auerbach, R Ovadia Yosef, R Moshe Feinstein).
If you take your medicine with water
- if you only drink the water for the medication and it has no taste, then there is no blessing (neither on medication nor on the water)
- if you are thirsty and would enjoy the water, you can say sheakol, drink some water then take the medication with more water -- this is also the way to get out of a doubt if you still have one
Sources: R' Forst sefer on brachos, Nishmat Avraham 204:8, this related MY answer
PS. There is no specific bracha on oil (petrol) - although you wouldn't need one anyway as it is (presumably) disgusting and (presumably) of no nutritional value.