Question: During Pesach, is it permissible for those who do not eat "kitniyot" (legumes) to use canola oil and products containing "liftit"? 

Answer: Permit me a brief introduction to the whole subject of "kitniyot" on Pesach: the reason for the Ashkenazi custom not to eat kitniyot (rice, corn, peas, beans, chickpeas, lentils etc.) is extremely unclear. Most of the commentaries maintain that 
since legumes may be used to produce types of flour that resemble wheat flour, there arises the possibility of confusion - and therefore they are forbidden. The truth is that when the Ashkenazi sages prohibited kitniyot, potatoes had not yet been discovered. When potatoes became common in Russia and Poland in the 19th century, the halakhic authorities there wanted to include them within the category of "kitniyot" because they, too, could be used to produce flour resembling "hametz". People began to panic that they would have nothing left with which to feed their families on Pesach. Ultimately the Ashkenazi sages ruled that "What was decreed, was decreed": since the original prohibition had not included potatoes, it was permissible to use them on Pesach. 

In addition to all of this there is a controversy among Ashkenazi authorities as to whether the fluid or oil that may be pressed from "kitniyot" is included within the decree of "kitniyot" or not.

Despite the difficulties involved, all the Askenazi sages during the past two centuries have maintained the prohibition against kitniyot, except in cases of famine and extreme need (as, for example, in Israel during the War of Independence). Therefore, 
all Ashkenazim must observe this prohibition. "Liftit", and canola oil which is derived from "liftit", do not appear to have been included in the original kitniyot prohibition, and therefore we may conclude in their regard that "What was decreed, was decreed, and 
what was not decreed, was not".

I must add a further point: every year I receive a great number of questions about kitniyot - usually concerning oil derived from kitniyot. This is undoubtedly an important issue, but the prohibition in question is based solely on Ashkenazi custom; it is doubtful whether these products were ever considered to have been included within the original decree. I receive far fewer questions about the possibility of keeping "hametz" in one's house during Pesach, in view of the explicit verse in the Torah: "On 
the first day you shall remove ("tashbitu") leaven from your houses".

I make every effort to ensure that the sale of hametz is a genuine and binding one, but the "loophole" of selling hametz is really a concession for those who will truly suffer considerable monetary loss if they are forced to destroy all hametz in their possession, as the Torah requires. (The Ba'alei ha-Tosfot interpret the word 
"tashbitu" to mean "destroy".) For most regular householders, it is preferable to destroy the hametz in one's possession (of course, it is possible to fulfill the requirement of "tashbitu" by consuming all the remaining hametz before the "fifth hour" on Erev Pesach).
At the very least one should remove all hametz from the house and give it to Bnei Akiva or some other organization that will distribute it to the needy after the festival.

Best wishes for a happy and kosher Pesach!