PokerStars Pot-Limit Omaha High, $0.25 BB (6 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

Button ($20.10)
SB ($28.75)
BB ($26.55)
UTG ($11.45)
MP ($17.45)
Hero ($13.20)

Preflop: Hero is CO with T, 5, Q, T.
2 folds, Hero calls $0.25, Button calls $0.25, SB completes, BB checks.

Flop: ($1) 4, T, 8 (4 players)
SB checks, BB bets $0.75, Hero raises to $3.2, Button calls $3.20, SB folds, BB calls $2.45.

Turn: ($10.60) 4 (3 players)
BB checks, Hero bets $6.5

Thoughts? Do I bet less to extract more value or is a 2/3 pot size bet just the right amount considering they both called my flop pot?

Bet anywhere from $0.25 to $10.60.

...(j/k)

This is dependent on your opponents tendencies, but I usually bet half-pot without a read. Two thirds pot should be fine as well. If you know you're against a calling station who overvalues his holdings and chases draws, go ahead and pot it. If you have a maniac yet to act, you can even argue for a check-raise (although I only use this play if he is over 95% guaranteed to bet here).

EDIT: I just noticed your chip stack. You have $9.75 remaining on the turn. In this situation, betting $6.50 makes no real sense. Either bet $4 or just shovel. I lean towards the $4 bet when I'm against maniacs who would interpret that as a weak bet and would raise me. Similarly, calling stations often intend to call, but when faced with an allin, they sometimes pause and actually think, "hey... should I be calling this?" Often the $4 bet will trap them to call the rest on the river anyway. If you choose to shovel, that's fine too.

You really can't go wrong with your bet size when you hold such a big hand on the turn and have less chips remaining than the full pot.

EDIT 2: what was I thinking? The $4 bet into maniacs is terrible. You kill their opportunity to try to raise you off the pot by being so pot committed. I revise my advice: bet $4 into most players and check into maniacs (again, only if you're 95% sure they would take the opportunity to bet). Don't kick yourself if you just choose to shovel, that's fine too.

i would just push, you have less than a pot-sized bet so go ahead and get your money in

Check against idiots, bet 1/2 pot against weak-tights and shove against good players. Really though, it makes so little difference which alternative you choose that it's not much of an issue. FTR, at this level "idiots" are going to be the top demographic by a large margin. The chance that you're up against two "good players" is so unlikely that it's hardly worth considering.