Nine wins from nine for Saracens
The English champions maintained their stranglehold of Pool One with a bonus-point victory after scoring six tries that left them nine points clear of Ulster, who thrashed record four-time champions Toulouse 38-0 on Friday and have a game in hand.
It was a ninth straight win in all competitions for Sarries who also lead the English Premiership after a perfect six from six start in domestic competition.
On paper, Sarries looked too strong for the Top 14 basement sitters, and that proved the case in a dominant first half in which the Oyonnax scrum was crushed time and again.
England flyhalf Owen Farrell had given the visitors an early lead from the boot before referee Marius Mitrea awarded a penalty try on 18 minutes after Oyonnax collapsed at the scrum.
Farrell was then the architect of a second try when his break and long pass to Chris Wyles allowed the American wing to pop the ball inside for full-back Alex Goode to scamper over down the left.
Moments later, Wyles popped up on flank Will Fraser's shoulder after another break from Farrell to go over under the posts.
Farrell kicked all three conversions as Saracens turned around leading 24-3 at the break.
The bonus point came in the 49th minute as Saracens worked an overlap on the left and flank Michael Rhodes drew in the defence before passing inside for lock Maro Itoje to go over.
A minute later, South African Rhodes almost went the whole way himself but after being caught 10 metres shy of the line, he found scrumhalf Richard Wigglesworth to add try number five.
There was still half an hour to go but the game was dead and Saracens lifted their foot off the pedal.
It allowed Oyonnax replacement scrumhalf Arthur Aziza to claim a well-deserved try late on for the persistent hosts, although Sarries still had the last word when South African Schalk Brits burrowed over.
The scorers:
For Oyonnax:
Try: Aziza
Con: Lespinas
Pen: Clegg
For Saracens:
Tries: Penalty try, Goode, Wyles, Itoje, Wigglesworth, Brits
Cons: Farrell 5, Hodgson
Pen: Farrell
Teams:
Oyonnax: 15 Quentin Etienne, 14 Silvere Tian, 13 Guillaume Bousses, 12 Alaska Taufa, 11 Dug Codjo, 10 Rory Clegg, 9 Fabien Cibray, 8 Pedrie Wannenburg, 7 Olivier Missoup, 6 Valentin Ursache, 5 Geoffrey Fabbri, 4 Leon Power, 3 Horace Pungea, 2 Jeremie Maurouard, 1 Soane Tonga'uiha.
Replacements: 16 Thomas Bordes, 17 Lukas Rapant, 18 Marc Clerc, 19 Antoine Guillamon, 20 Pierrick Gunther, 21 Florian Faure, 22 Arthur Aziza, 23 Regis Lespinas.
Saracens: 15 Alex Goode, 14 Chris Ashton, 13 Marcelo Bosch, 12 Brad Barritt (captain), 11 Chris Wyles, 10 Owen Farrell, 9 Richard Wigglesworth, 8 Billy Vunipola, 7 Will Fraser, 6 Michael Rhodes, 5 Maro Itoje, 4 Jim Hamilton, 3 Juan Figallo, 2 Jamie George, 1 Mako Vunipola.
Replacements: 16 Schalk Brits, 17 Rhys Gill, 18 Petrus Du Plessis, 19 Kelly Brown, 20 Jackson Wray, 21 Neil De Kock, 22 Charlie Hodgson, 23 Mike Ellery.
Referee: Marius Mitrea (Italy)
Assistant referees: Matteo Liperini (Italy), Stefano Pennè (Italy)
TMO: Carlo Damasco (Italy)
Sources: AFP & @ChampionsCup