In the late 1960s, he moved to Los Angeles where his drum work was utilized by artists including Frank Sinatra, The Beach Boys, George Harrison, Frank Zappa, The Animals, Joni Mitchell, Them, Thelonious Monk, Lou Rawls, Ray Conniff, George Shearing, Peggy Lee, Ella Fitzgerald, Linda Ronstadt, Nelson Riddle and many others.

Guerin was an exponent of the jazz-rock style and played in many different genres, including for film and television.

[1] Among his contributions to motion picture and television scores, Guerin worked on the soundtrack to the 1988 film homage to Charlie Parker, Bird by Clint Eastwood.

In later years, Guerin worked with Oscar Peterson, Jon Faddis, Jimmy Heath, Ray Charles, Sonny Rollins, Justin Morell, Andreas Pettersson, David Basse, David Garfield, Gary Lemel, and Mike Melvoin.

[2] With David Axelrod With The Beach Boys With Pat Boone With Michael Franks With Terry Garthwaite With David Gates With Jack Jones With Peggy Lee With Melanie With Joni Mitchell With Oliver Nelson With Aaron Neville With Tom Pacheco With Howard Roberts With Emitt Rhodes With Linda Ronstadt With Diane Schuur With Seals and Crofts With Bud Shank With Frank Sinatra With O. C. Smith With Patrick Williams With Frank Zappa With others