I never used grease. What I did to figure it out: took gas cap off, VERY carefully pried it apart, without breaking it, then epoxied all the air holes & so it did not "click" anymore. Meaning, you could REALLY tighten it up, with no stupid clicking. Heating it up in hot water helps make the plastic less brittle when prying it apart. After it cured for a couple days, I put it back on. After a week, the light went out. So then I went back to dealer & told them the new cap was faulty. They gave me a new one. The factory ones only lasted about 6 months. I think i still have the epoxied one around somewhere, but i don't know where. Got lost in the garage somewhere. I have been using it since 2000, as my Dakota, 2004 & 2008 all have/had the same gas cap.
NOTE: I did open it when i got home from work & again before i started truck. I did not want it to vapor lock while driving. Everytime I opened it, i could hear the air come out. Kinda the same sound as when you open a jar, only air came out, instead of going in.
Traded to 2019 ZR2, Red.
4Runner was a GREAT vehicle but could not even tow our 6x10 enclosed utility trailer comfortably, even when it was empty-ish.
It was time. Truck was still leaking BADLY every time it rained or snowed & melted. It was leaking at every single gasket (rear window, front window, all 4 doors). You could sit inside & watch it run down the inside of windshield, rear window & drip off the upper side door beams. It was molding on the inside & starting to stink. Needed new steering gearbox, shocks, new upgraded T-style steering, tires, brake lines, d/s manifold bolts that are barely recognizable due to rust-removed & replaced. Everyone around here would not even touch em once they looked at them.
So, say what you will. PW turned into a money pit. Was no longer a joy to drive. Hoping that this downsized 4x4 with lockers will fill the bill & have minimal problems, but..... As long as manufacturers keep making engineers design things that fail soon after warranty is up, we are going nowhere fast. Regardless of what you buy.