U.S. oil prices dipped on Friday after an early rise to 2016 peaks, but posted a gain of about 20 percent for April, the largest monthly gain in a year.
Futures held losses after oilfield services firm Baker Hughes reported its weekly U.S. oil rig count fell by 11 to 332. At this time last year, drillers were operating 679 oil rigs.
A weaker dollar and optimism that a global oil glut will ease have boosted crude futures about $20 a barrel or more since they plumbed 12-year lows below $30 in the first quarter.
With prices less than $5 away from $50 a barrel, investment bank Jefferies said the market "is coming into better balance" and would flip into undersupply in the second half of the year.
But others warned that the rally was driven by investors holding large speculative positions, while oil stockpiles were still high, with a Reuters survey showing OPEC output in April rising to its most in recent history.