Portuguese teenager Oliveira, who had qualified eighth, fended off a fierce two-bike attack in the closing corners to earn eight points for the side.
Spanish Vazquez had qualified fourth and was running strongly in the group until an oil-control issue struck his Mahindra MGP3O machine, and he was forced to retire.
Mahindra Racing CEO Mufaddal Choonia was pleased with Oliveira's effort and relieved their machine did not have any major mechanical issue.
Oliveira was not content with eight-points performance.
"I am not really happy. Eighth is certainly not our place. But today was very hard - I was struggling a lot for grip from the tyres. We lose a little acceleration to the KTMs at the moment, and there are two very small first-gear corners on this track, and a long straight. I aimed for a safe race, try not to crash, and get some points. I just tried to defend myself and my position, and that was successful," the 18-year-old said.
