He did about three years of stage/repertory work, and his first film was in 1912 for Selig. More film work followed at Lubin and Selig, and it was at Universal circa 1917 that he met Priscilla Dean, and they married in 1920. Oakman enlisted in the US Army Artillery during World War I, and was discharged as a Corporal. In the mid 1920s, there were marriage problems and a divorce. Oakman briefly returned to the New York stage but returned to Hollywood and film work. There were two more marriages and two divorces.

While Oakman did westerns, he's probably best remembered wearing a suit or tuxedo, and portraying a gangster, a slick crook, a gambler or a detective. As mentioned, his film career began around 1912, and he worked in about 150 silents. His sound era appearances amount to about 125 films, of which 36 are westerns and 16 are serials. Nearly half of his sound B westerns were 1930s Tim McCoy adventures at Columbia, Puritan and Monogram.

Some memorable Oakman roles in oaters and serials:

• in SUNDOWN RIDER (Columbia, 1933), the "branded" Buck Jones tracks down Oakman, the man who framed him as a rustler.
• in IN OLD SANTE FE (Mascot, 1934), Oakman was among the no-goods trying to appropriate Tarzan from Ken Maynard.
• Oakman was "Argo, the High Priest" versus Gene Autry in THE PHANTOM EMPIRE (Mascot, 1935) chapterplay.
• Oakman was "Ace Barko", a member of the gang harassing ranch owner Frank LaRue and his daughter Ann Savage in the Russell Hayden SADDLES AND SAGEBRUSH (Columbia, 1943).

By 1940, Oakman had slowed down because of heart problems, and his credited and uncredited roles during the decade of the 1940s amounts to only thirty or so films. He and producer Sam Katzman must have been friends as Sam used Oakman frequently at both Monogram and Columbia: he was in three Bela Lugosi cheapy horror films, one of which included the East Side Kids; he did two other East Side Kids comedies; and he also worked in seven Katzman cliffhangers. Oakman's last work was in the Katzman produced SUPERMAN (Columbia serial, 1948). During those later years, he was the assistant manager at a theater in North Hollywood.

One other tidbit on Oakman - I checked Jack Mathis' Republic Confidential - Volume 2 - The Players (published by Jack in 1992), and was surprised that Oakman did only two at Republic Pictures, DARKEST AFRICA (Republic serial, 1936) and THE LONE RANGER RIDES AGAIN (Republic serial, 1939). Mathis also lists a third title with Oakman - the short MEET THE STARS #8: STARS PAST AND PRESENT (Republic, 1941).

Wheeler Oakman passed away from a heart ailment at his North Hollywood home on March 19, 1949.

The Family Search website (free), Ancestry.com (subscription), the California Death Index, and the death certificate provide more about Wheeler Oakman:

• 1900 census: living in Washington D. C. are 58 year old Frank Eichelberger (born Maryland), his 42 year old wife Minnie (born Virginia), 10 year old son Vivian Eichelberger, and three more siblings: https://familysearch.org/pal:/MM9.1.1/MMFQ-VKQ
• World War I draft registration dated June 5, 1917: 27 year old Wheeler Vivian Oakman is married and resides at 2401 W. 9th, Los Angeles, California. He was born February 21, 1890 in Washington D. C.; occupation and employer are "Actor" and "not employed at present": https://familysearch.org/pal:/MM9.3.1/TH-1942-26181-30946-83?cc=1968530
• 1920 census: living in Los Angeles are 38 year old May Preston Dean (born New York), her 21 year old daughter Priscilla (born New York; this is actress Priscilla Dean), 29 year old boarder Wheeler P. Oakinair? [sic] (born Washington D. C.) and another boarder: https://familysearch.org/pal:/MM9.1.1/MHQF-FX2
  Ancestry had the 1920 census takers worksheet: could not decipher their Los Angeles home address. Wheeler is listed as married, but Priscilla is single. The occupations of Priscilla and her mother are "Actress-Motion Pictures", and Wheeler is "Actor-Motion Pictures".
• September 19, 1927 Los Angeles county marriage license of 37 year old Wheeler Vivian Oakman (born Washington DC) to 20 year old Virginia Mae Jennings (born Nebraska): https://familysearch.org/pal:/MM9.3.1/TH-1942-29941-2752-39?cc=1804002
• Birth index for Wheeler Oakman Jr., born December 18, 1928 in California and mother's maiden name was Jennings: https://familysearch.org/pal:/MM9.1.1/V2R3-RQH
• 1930 census: living in Los Angeles are Wheeler V. Oakman (born Washington D. C.) and James P. Hogan (born Massachusetts): https://familysearch.org/pal:/MM9.1.1/XCVM-9WX
  Ancestry had the 1930 census takers worksheet: Hogan is the head of household and is renting at 1953 1/2 Vista Del Mar, Los Angeles. Occupation of Hogan is "Director-Motion Pictures" and Oakman is "Actor-Motion Pictures". Both are married (but no wives are present) and both answered "Yes" and "WW" (meaning World War I) to the are you a veteran question.
  The Internet Movie Database has more on director James P. Hogan (1890-1943): http://www.imdb.com/name/nm0003373/
• 1940 census: 50 year old Wheelie [sic] Oakman (born Washington D. C.), 39 year old wife Mary T. (born Texas) and a lodger are renting in Los Angeles: https://familysearch.org/pal:/MM9.1.1/K9CD-KV2
  1940 census takers worksheet: the Oakmans are renting at 2028 Blackwood Drive, Los Angeles. He completed one year of high school; occupation is "Actor-Motion Pictures", and in 1939, he worked 18 weeks and earned $1305.00: https://familysearch.org/pal:/MM9.3.1/TH-1961-27797-2801-90?cc=2000219
• 1942 World War II draft registration: 52 year old Wheeler Vivian Oakman was born February 21, 1890 in Washington D. C. He lives at 1623 Broadview, Glendale, California. His contact is the Screen Actors Guild and his occupation/employer is "free lance actor" and "Motion picture studios": https://familysearch.org/pal:/MM9.3.1/TH-1-16372-90858-32?cc=1861144
• Death certificate: Wheeler Vivian Oakman was born February 21, 1890 in Washington, D. C.; his parents were F. F. Eichelberger and Mildred Watkins. Was a World War I veteran (serving from 2/13/1918-1/26/1919); occupation was "Retired Actor" and "Theater Manager"; and he was divorced. He passed away March 19, 1949 at his home at 13021 Chandler Boulevard, North Hollywood, California. An autopsy was performed and cause of death was coronary occlusion. Burial at Valhalla Cemetery, Burbank, California. Death certificate informant was his son, Wheeler Oakman, Jr.
• California Death Index has a record for: Wheeler Vivian Oakman, born 2/21/1890 in the District of Columbia, Mother's maiden name of Watkins, and he passed away in the Los Angeles area on 3/19/1949. You'll also find a second Wheeler Oakman record, which is for his son: Wheeler Oakman, born 12/18/1928, Mother's maiden name of Jennings, and he passed away in the Riverside, California area on 6/17/1992.

  Although some of the data is incomplete or inaccurate, the Internet Movie Database (IMDb) has information on Wheeler Oakman: https://www.imdb.com/name/nm0643048/

Find A Grave website notes that Oakman is interred at Pierce Brothers Valhalla Memorial Park, North Hollywood, California: https://www.findagrave.com/memorial/14769745/wheeler-oakman
(I asked contributors Jim Sorensen and Dale Crawford about Oakman's burial info and they confirm he is interred at Valhalla but there is no marker.)

There's a circa 1919 photo of Oakman at the American Film Company (nicknamed the "Flying A") website which is maintained by the University of California at Santa Barbara. When you get to this webpage, click on the letter O, and scroll down the listing for Wheeler Oakman: https://flyinga.filmandmedia.ucsb.edu/people/index.html

There's several circa 1924 photos of the large Beverly Hills home of Oakman and wife Priscilla Dean at the Silents Are Golden website: http://www.silentsaregolden.com/homes/homedeanoakman.html