TxBriley - excellent question, as I had the same one before my first fuel fill-up!
On my 2015 Platinum, it was on the floor held in place by a clip in the bay underneath rear seats directly behind the driver's seat (left rear passenger)
On my 2018 Platinum, it is tucked onto a fabric seam behind the right rear passenger seat
= You need to pull the top half of the right rear passenger seat forward
= Factory funnel is tucked about half-way up the frame by the door jamb
This is a better spot as it doesn't take up what little space is available in the old spot on my 2015.
Full disclosure: I cannot take full credit for this, as my Service Manager pointed the new location out to me.
they are also on amazon for $7 if you need a spare.
I can validate this statement. The first time I was going to put additive in my tank before a fuel up I tried using a funnel very similar to this one https://www.amazon.com/WirthCo-32855-Funnel-Multi-Purpose-Capless/dp/B00L4816B4/ref=pd_bxgy_263_3/135-8060252-0704839?_encoding=UTF8&pd_rd_i=B00L4816B4&pd_rd_r=036a04d2-5086-11e9-9b47-850ae58408d8&pd_rd_w=OoeE9&pd_rd_wg=ISMqm&pf_rd_p=a2006322-0bc0-4db9-a08e-d168c18ce6f0&pf_rd_r=D6KN95FTDG7F49AMTRY8&psc=1&refRID=D6KN95FTDG7F49AMTRY8 that I purchased at my local Fleet Farm, inserted it into the capless inlet, started pouring in additive and discovered that the additive was not going down into the tank.The smaller diameter funnels dont work. Has to match the factory diameter or the second flapper wont open.
Have you been able to test this working for our capless inlet?I did buy this adapter just in case I was stuck with only big rig pumps. Works in a bind but it is good for adding additives. Nice with the case to to keep the smell contained.
It works for sure. Used it a bunch of times. Haven't used a bigger nozzle pump yet as I am keeping that as emergency only but it works for additives.Have you been able to test this working for our capless inlet?I did buy this adapter just in case I was stuck with only big rig pumps. Works in a bind but it is good for adding additives. Nice with the case to to keep the smell contained.