Check your oil level using the dipstick. If the level is just a bit low through normal oil consumption but there is still plenty in there, my advice would be to get hold of the oil you normally use absolutely as soon as possible, rather than put the 'wrong' stuff in. In future, I recommend manually checking the oil level with the dipstick at least every couple of days; the oil level warning is calculated, not directly measured and cannot be relied upon.
If you have hardly any oil at all in the car, maybe through putting the oil cap back on incorrectly and it leaking, put the oil you have bought in. The wrong oil is better than no oil.
A dipstick reading and reason that the car is so low on oil will help us give more conclusive advice.