John Frusciante

John Frusciante plays his Martin 0-15 in the official music video for Road Trippin'.

In this scan from the magazine Guitar World Acoustic (USA), April/May 2005 issue, Frusciante is asked, "Do you write all your songs on acoustic guitar?" He confirms that he owns a 1940s Martin 0-18:

FRUSCIANTE: "Pretty much, although sometimes I write on an unamplified electric guitar. I have a few old Martins, two small-bodied 0-15's and an 0-18, at my house that date from the Forties. I usually write songs on one of those. And I always bring a couple of acoustic guitars on the road with me to write with. Writing songs on an unamplified electric has its drawbacks. The guitar is so quiet that I sometimes sing in a high falsetto voice that doesn't really work when I do the final recording. So I've learned to write on the acoustic and actually sing in the style that I want to use on the final recording."

He played this Martin in 1991 on a boat with Anthony keidis In Amsterdam

In this source you can see John Frusciante with a 1973 Martin D-12-20.

In this photo, John Frusciante can be seen playing a Martin D-18 (it is not a D-28 as there is no white binding around the body). This same guitar can be seen in John Frusciante's bedroom on the documentary "Funky Monks", filmed during the recording of "Blood Sugar Sex Magik" (see at 57:05 on this link : https://www.youtube.com/watch?v=4Z3Gnbgjq0M). This Martin D-18 is therefore possibly the instrument used during the recording of the song "I Could Have Lied". It is possible to notice that the bridge pin of the G string on this guitar is white while the others are black ; this bridge pin was certainly swapped with one of the bridge pin of the 12-strings guitar used by John Frusciante during the recording of the song "Breaking The Girl" (this 12-strings guitar has 11 white bridge pins and 1 black bridge pin as you can see in the photo of this link : https://www.groundguitar.com/john-frusciante-gear/john-frusciantes-12-string-acoustic-breaking-the-girl).