Actually - I would tell you from my own experience: the triglycerides are ignored if the Cholesterol is in reason. Triglyceride increase can be a sign of other things. A low carb diet is simply not the answer. Tryglicerides are kinda like a fat, but not exactly. They metabolize better when we are young and not so well when we are older. They can signal a metabolic disorder. https://www.nhlbi.nih.gov/health/high-blood-triglycerides#:~:text=Triglycerides%20are%20a%20type%20of,does%20not%20need%20right%20away.
Re: Corn oil is an EXCELLENT way to lower serum cholesterol, has healthy linoleic acid, and has a high smoke point! So many, many great things about it - Grandma was right even though she didn't know it!:
https://pubmed.ncbi.nlm.nih.gov/2258533/#:~:text=Refined%20corn%20oil%20is%20composed,n%2D3%20ratio%20of%2083.
As far as the hexanes - there are different types - and you are right they should be replaced. I don't consume much oil except during the holidays when cooking, but I use very high-quality oils to be sure! I'll check out the book! Always interested in learning more!