All the time. Seriously. Cap and Wolverine are both heroes, but have wildly different worldviews.
Unfortunately, they've fought so often, and usually with such a narrow margin if "who won", that it's really impossible to call either one a clearly superior fighter.
This blog goes over some stats and historical battles between the two. They note that of the twelve matchups that they selected to focus on, Cap came out on top 5:1, but acknowledges the fact that often times, the win was very fuzzy.
- CAPTAIN AMERICA ANNUAL #8: Draw
- THE X-MEN VS THE AVENGERS #1: None
- THE X-MEN VS THE AVENGERS #4: None
- INFINITY WAR #2: None
- CAPTAIN AMERICA #404: Wolverine
- CAPTAIN AMERICA #405: Captain America
- WOLVERINE: ORIGINS #4: Captain America (Edge)
- WOLVERINE: ORIGINS #4: Wolverine (Edge)
- WOLVERINE: ORIGINS #5: Captain America
- WOLVERINE: ORIGINS #20: Captain America
- AVENGERS VS X-MEN #3: Captain America
The problem is that largely speaking, they're pretty well matched, so it really comes down to a matter of circumstances and the specific writer of the story. For example, in Avengers vs X-Men, Wolverine was doing pretty well against Cap before the rest of the Avengers intervened to end the fight prematurely.