Buchanan claimed Pietersen has distanced himself from his team-mates and dictated where he bats in the order.
The usually understated Buchanan said he had not seen any evidence suggesting the tourists' most assured batsman was a team player.
England Friday confirmed Pietersen had batted one spot higher at No.4 in the second innings of this week's fourth Melbourne Test because he was tired of batting with the tailenders when batting at No.5. in the one-sided series.
Australia are shooting for the first 5-0 Ashes clean sweep in 85 years in Tuesday's fifth Sydney Test after crushing England by an innings and 99 runs in Melbourne Thursday.
Australia, in particularly star spinner Shane Warne, questioned why England had waited until third drop before sending in its most destructive batsman.
But Buchanan Friday said Pietersen would be determined to bat at No.4 so he could impose himself on the fifth Test.
"I would be expecting Pietersen to be constantly chipping away at (England coach) Duncan Fletcher about where he bats and how he can impact on the game," Buchanan told reporters here Friday.
"Now he has got the opportunity, so let's see him deliver that in Sydney if that's where they stick with him."
Pietersen has scored 420 in the series at an average of 60 and scored 158 in the first innings of the second Adelaide Test.
Buchanan said Pietersen often appeared removed and distant from his team-mates on the field, given he was a good in-fielder but spent a lot of his time patrolling the boundary rope.
He said different characters were essential to any side, but made a point of singling out the high-profile Pietersen.
"Pietersen certainly talks about himself as a team player and I don't personally see any evidence of that, but that's from a distance," Buchanan said.
"I'm not in their dressing room, but he could be one of the greatest team men of all time.
"That's a question for you to pose to Pietersen or England team management."
Pietersen, who spent 2005 batting at No.5 for England, batted at No.4 for most of 2006 and then dropped down for the Ashes series. He averages over 50 in both positions.
Fletcher said Pietersen felt most comfortable batting at No.5, but had asked him and captain Andrew Flintoff for a promotion because he did not want to be again stranded with tailenders.
In four of seven innings this series where Pietersen batted at five, he either holed out chasing quick runs or was left not out after running out of partners because of England's brittle lower order.
KP discussed a promotion with Fletcher and Flintoff halfway through the MCG Test, Fletcher said.
"He said 'I'm batting with the tail a lot, I'd like to bat four'," Fletcher said.
"We said 'Are you sure you want to bat four and move up?', and he said 'I'd prefer to bat at four instead of being caught with the the tail we've got at the moment'.
"So we said 'Go in at No.4'. Kevin will bat four right through the Sydney Test match."
Fletcher said Paul Collingwood had been supportive of swapping positions because he recognised Pietersen was the tourists' best batsman.