Shen Qiuhua recalled the past when she spoke of such things. She remembered how tough things were back then since the family could not afford to waste even a drop of oil.
She was only willing to use more oil now that her family's conditions had improved. However, the oil they had produced from the roasted peanuts was insufficient, so they could not cook.
In other words, the family was only willing to use the oil they harvested and would not buy it because of how expensive it was. No one was willing to spend on oil and would save as much money as possible.
Shen Qiuhua would peel peanut kernels in the past and keep a portion to use as seeds for the following year. Then she used the rest to roast and make peanut oil.
She typically stored the peanut oil she produced in a large jar and kept it for a year because the family had to wait to harvest more peanuts the following year before making more oil.