Let’s face it India is acting out of economic self interest. Trump will have to use a variety of carrot and stick.
Besides that, India has a long history of cooperation with the Russians / Soviets.
So they may think Russia can help them with China.
You seem to know a lot about the situation. Is India producing this oil or just a middle man? Why can’t Russia get oil from Iran?
Russia isn't buying oil from India, it's the reverse. India is the one buying Russian oil. When the EU put sanctions on Russia over the Ukraine war, they stopped purchasing oil from Russia and tried to procure from the Middle East which was where India bought oil from. To prevent oil prices which was around $100+ from increasing further, the US government encouraged India to buy Russian oil to keep the market stable. EU still needed high speed diesel so they said that if Russian oil is refined in a 3rd country, it would not be classified as Russian. They then bought that diesel & aviation fuel from Indian refineries whose inputs included Russian oil.
Now the Trump administration is sanctioning India for buying Russian oil which the previous Biden administration had encouraged. Little wonder the Indian government is upset over the sudden change in the US position.