There’s something oddly reassuring about Liam Gallagher’s inability to be anything other than his unswerving absolute self. Asked recently if Oasis had considered putting out their new album as a free download, the monobrowed singer revealed his neophobia in a way that only he could. Eccentrically. “Look, I’m trying salmon, that’s as far as my interest in new things goes,” he declaimed impatiently.

Two days ago, then, when all of the new album appeared (albeit in a non-downloadable form) on their MySpace page, you suspect that Liam may not have even been aware of the fact – less still his brother. Noel’s mistrust of progress has pretty much informed Oasis’s lack of it over the last decade.

While their two most notable rock contemporaries, Thom Yorke and Damon Albarn, have shed skin after skin to keep themselves artistically relevant, Oasis have merely turned up the volume, lowered their heads and peddled workmanlike Brit rock. As Noel Gallagher has confessed, he may never write another Live Forever or Wonderwall. But when your band is a Grateful Dead for the new Labour years then your fanbase will continue to be here now for you, through good times and bad.

Which is something of a mixed blessing. On the cement-footed Don’t Believe the Truth in 2005, Noel Gallagher sounded like a man who could use a little pressure to raise his game. But Dig Out Your Soul suggests that Oasis may be dipping their toes into experimental waters, and enjoying the sensation.

What the online move this week illustrates is that someone somewhere believes that Oasis have produced some music to rival those high-water marks. They’re not wrong. Noel Gallagher is no longer possessive about appearing in the credits of every Oasis song. Liam turns in an unprecedented three contributions, while the bassist Andy Bell and guitarist Gem Archer chip in with one apiece. And somewhere amid the relative seclusion of his rural retreat, Noel’s writing appears to have acquired a renewed sense of urgency.

There’s very little on Dig Out Your Soul that’s as adventurous even as trying salmon for the first time. That said, there are moments where you feel like flinging your arms around the Gallaghers for the modest innovations: the hypnotically sluggish rhythm that pushes along Liam’s stoned vocoder vocal on Get Off Your High Horse Lady; the demonic swamp rock of Waiting for the Rapture, executed with febrile intensity.

It’s an album that maintains an irresistible atmospheric pull for sustained periods – and that’s an advance on anything the band have offered this decade. Certainly, they’ve written nothing that sounds quite like The Turning, a moody five-minute beauty that moves from a tentative electric piano and climaxes with a nocturnal FM rock climax.

At this stage, an Oasis album that totally divests itself of all Beatles influences is asking a bit much. Gem Archer’s sole compositional contribution, To Be Where There’s Life, charges along on a bassline, played by Bell, that may push Paul McCartney’s eyebrows up into the realms of physical implausibility. Falling Down deploys an identical rhythm to the one invented by Ringo Starr on Rain, but it’s being played by Ringo’s son Zak Starkey. More importantly, it sits at the centre of another Oasis song that corresponds to little else in their canon – a rain-lashed, nocturnal hymn to uncertainty and vulnerability.

Of course, vulnerability isn’t something on which the older Gallagher has a monopoly. But the brothers’ ways of showing it couldn’t have been more different. On the rare occasions that Noel has sung Wonderwall it has sounded like a 2am cry for help. The reason Oasis became a social phenomenon, though, was because Liam could sing the same lyrics and sound like a man who could punch a hole through a door to prove how f***king sensitive he is.

But Wonderwall was a long time ago. And if Liam was the same person that he was in 1995, he surely couldn’t have sustained a quiet family life with Nicole Appleton over the years. It’s a view lent some weight by I’m Outta Time. Like every song that Liam will ever write, the John Lennon influence is unavoidable. But, over the course of his most tender vocal to date, he sounds oddly, movingly enraptured. Another first.

Relaxed as Noel is, three Liam classics on one album might have been a bit much to stomach. So it may be no accident that the other two Liam songs aren’t quite up to the same standard. Of Ain’t Got Nothin’ and Soldier On, one was a discarded song unearthed only at the last minute. But which one? Surely the former, a Who-style sonic dust-up of minimal melodic traction?

Actually, it’s the far superior Soldier On. Here, Liam’s reflective paean to perseverance oscillates soberly between a single titular mantra and bursts of keening melodica from Noel, until both dissipate, as if to leave room for closing credits. Could you really have been listening to the best Oasis album since Definitely Maybe? Maybe not definitely. But definitely more than maybe.

To order Oasis, Dig Out Your Soul for £13.99 call 0845 6026328 or click here to order online.

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