It started off with a rattle from a new car which I assumed would go away as part of the breaking in process. Our gas mileage fell to 16 MPG so I changed the oil at 1600 miles. Oil was full of metal flakes and chunks. The gas mileage got better for a few weeks, then the knocking got worse and gas mileage went down. I sent the pictures of the metal to Toyota Corporate and after a few weeks they emailed me back and told me to call the 1-800 number. After speaking to them, they made an appointment for me at my local Toyota dealership.

I brought it in on December 18th, 2019 (2 months and about 2700 miles of ownership in). The dealer had a tech do a ride along with me and we didn't really make it past the car lot when it started knocking at all RPMs, where before it would have to be over 3k RPM to exhibit knock. Bakter Toyota of Lincoln already had us set up with a loaner car, per my request when the appointment was made. I got a phone call from them a few hours before they closed saying it was getting new parts and it would probably be a new short block and maybe a few other parts. The service guy we had, Ethan, has been amazing.

I have owned lots of brand new cars, all with some sort of problem, but this was by far the best service I have ever had so far. The loaner we got only seats 5 so I asked them for one with more seats and told them our Highlander seated 8, so in January they will be switching us over to a van. Again such great service, and he made sure our needs are met while taking care of our problems. I was able to find one other person that had a 2GR-FKS engine with metal in the oil in a 2016 model year, and they had their engine replaced as well. They advised me to contact Toyota Corporate before the dealer, so when I got to the dealer they said I had already started the process for them. This is our first Toyota and the first time I have had to replace an engine in a vehicle. I'm hopeful they can get the engine right and there will be no lingering problems.

Update from Jan 31, 2020: Dealer found chunks of rod bearing in the oil pan. Replaced the engine with a short block. Toyota gave us a complimentary extended warranty.