5.7 oil filter seal ring?

Help if you know. I'm want to verify or find out where the quad ring in the photo is supposed to go, I'm assuming it goes up inside the oil filter housing since I found it lying under the engine when I slid back under to install the new filter, but there is the possibility it came out of the cover or socket upon removal, since they all have the same size boss OD in them (I tried and it does fit any of the three spots) but it could have fell off the cover or socket and I just didn't notice. It didn't fall during in any of the other filter changes I've done. It doesn't seem like it is vital as the element seats on the ID, maybe it keeps the pressure from collapsing the element?

 

You're referring to the smaller oring that comes with your new filter? It goes on the bottom of your filter housing..

I marked it in red here..

 

You should be changing two o rings every oil change. The large one that goes at the bottom of the threads on the filter housing and the small one at the housing drain plug. How have you done oil changes already and never noticed or changed these? They are 100% vital to to prevent oil from being pushed up of the housing.

 

Yes I change these 2 "O" rings every filter change, this is a Quad ring, about 1/4" square profile, approximately 2" ID.

 

Is that a spring in that "quad seal"?

 

No, it has a small raised spot in the center, or the edges are indented a little. Just not completely flat on shown side.

 

I’ve never seen that type of ring on any oil change. I’ve even changed out the plastic housing for metal and that was not anywhere in the housing.

 

I'm thinking it has to go up in the filter head housing, I'm just not sure having never looked up in there before. Tried to find it by looking up the parts exploded view of the the filter head but it only shows the housing and nothing else.

 

And this mystery seal had motor oil on it when you found it? Has anyone else changed the oil prior to you finding this quad seal?
I'm far from an expert but I've done about 5 oil changes on my 21 and don't recall seeing anything resembling that.

 

Looks like crush washer for the oil pan drain plug?

Actually looks to large for that

 

It wasn't dry, it had an oil film on it but not drippy. I had Toyota dealer do my first oil change (bought with 37K on it, dealers had always done it prior) this is the fourth time I've done it and have never seen it before, but how often do we look up into the housing after dropping the filter?

 

Way to big for drain plug and it was already back in with seal when this was found.

 

21 oil changes in my tundra. 8 oil changes in my wife’s highlander. Same oil filter setup. I’ve never seen this piece.

 

21 Tundra 18 oil changes. I also never seen this.

 

That looks like the seal on the underside of the oil fill cap.

Bet yours fell out when you took the cap off and you didn’t realize it.

 

Does not look like anything I've seen doing oil changes. The O ring under the drain cap is totally round, no raised spot. If it fits in there then that's probably where it came from, odd.. I've looked up into the oil filter housing and never seen anything like that..

 

That definitely isn’t for oil changes…..almost looks like it should be lining a grommet hole

 

I'm betting this is it.

This last oil change i found my oil fill cap gasket stuck on my MotivX funnel. I went at least one oil change without it.

 

now that you mentioned it, this happened to me too! You won the internet today!!!

 

Changing my oil today. Will look at oil fill cap and also see if I can see anything when I take filter housing out and get back to you.

 

100% that's the fill cap gasket