This is an emotionally and politically charged topic that can be hard to discuss with any clarity. The Skeptoid episode What the Oil Companies Really Knew, part 2 of which can be found here: https://skeptoid.com/episodes/4877, can be a good starting point because it is at least an attempt to try and provide a fair and factual overview.

I think this passage is particularly relevant:

> The message received from actually reading all of these documents is not — as is commonly reported — that oil executives' own scientists were warning them of the true nature of climate change. Instead, what they indicate is a broad pattern of scientists who were either outside their discipline or among the outliers who were unconcerned with the anthropogenic portion of CO2 buildup, advising those executives that no action was currently warranted. They were wrong, make no mistake; but that's what they were saying, and that's the information the oil companies were acting upon, at least through the end of the 20th century.

> There's a point I've tried to make any number of times on Skeptoid, and that's if you want your argument to be robust and persuasive, don't include any bad evidence. Include only strong evidence that has been proven to survive scrutiny. If you present cherrypicked quotes, like the authors of so many of these articles have been doing, it is very easy for your opponents to discover that; and when they do, the only point you will have made is that your argument is weak and easily countered — and thus probably false. It's a bad time in human history to harm the cause of educating people about global warming.