Scotty, I bought my first Toyota a 2017 Highlander Limited Platinum AWD in 2017. I have seen several posts that there is an oil leak issue with the 2017 model. At 500 miles I noticed a small oil drip on the garage floor. I took it back to the dealer, they kept the car for 3 days to drop the engine and fix the leak properly. The drip was from the front cover. Toyota covered the repair.
I went through the 2 year free regular maintenance and had several oil changes. No leaks. The car now has 23K miles and it was time for an oil change. The dealer informed me that the leak had returned. They asked me to drive the car 1k miles and come back for an inspection. I took the car back, said that they saw there was oil seepage, but not leaking. My factory warranty will expire in less than 12 months. They said that if the leak returned, I should contact Toyota and inquire about warranty repair. I really like the car, but I don't want a $2500 repair bill when the leak returns, What should I do, trade for a 2021 4Runner? I realize that I will loose all the fancy add-ons that the Platinum has, the 2021's don't have some of the same features.
IMHO, you should go above the dealer's level and contact the Zone. And check to see if there's a TSB on this issue, if you haven't done so.
Here's a list of the Technical Service Bulletins for the 2017 Highlander: https://www.carcomplaints.com/Toyota/Highlander/2017/tsbs/
Hardly a reason to trade in a vehicle. I agree with @geriscan, escalate the issue with Toyota & ask for a permanent fix.
You still have 12 months to weigh your options & give Toyota another opportunity to fix the leak.
Also consider having the vehicle inspected by an independent Toyota mechanic, to check if there are multiple sources of the oil leak.
