I've been using synthetic in all of my vehicles for years including my current 2 4Runners. My only suggestion would be to go ahead and change to a synthetic (I personally think Mobil1 is the best bang-for-the-buck but I use Amsoil in my Mustang) and watch for any leaks or smoking. And if it does leak or smoke a little, leave it in to see if it worsens or stops before you decide to change back.
I had a '97 Camry that had 35,000 miles when I changed to synthetic and it smoked at startup. I could have lived with it but the ex got that car and she switched back to dino.
My personal reason for using synthetic is not for protection but the change frequency that I went to from 3k miles with dino to 10k miles with synthetic. Since I drive about 2k-3k miles per month, I was simply changing oil way too often. And with alll the cars I've had, synthetic afforded me no additional engine life compared to dino oil with the change frequencies I noted above for each. My cars with dino vs. my cars with synthetic had no different oil useage or issues after 200k+ miles.