well, considering the most weight lifted ever is 6270lbs (Paul Anderson, in 1957), I'd say its safe to assume that they could both lift far more than that source says. However, that amount of weight was lifted with his back (and legs). The most ever bench pressed without the aid of any type of equipment such as a bench shirt, was 715lbs. So once again, safe to assume they could both probably do better than that.
Honestly, I'd be ok with the idea of Wolverine being stronger than Cap, and I love Cap. Despite it never officially saying that Wolverines mutation has resulted in super strength, he is obviously far stronger than any normal human could ver be, especially considering his size. You could read almost any comic he's in and infer that. He's really done some pretty ridiculous feats of strength. Thats not to say that Cap hasn't as well, cause obviously he has. But we know for certain, as in it is explicitly stated that Caps strength is not and can not be superhuman, whereas we don't know what the limit on Wolverines is. Seeing as how Deadpools mutation is derived from Wolverine, and Deadpool has superhuman strength, it would be pretty safe to say that Wolverine does too.