Does anyone knows if Engine Oil Consumption limits are part of the engine certification requirements?
Indirectly yes, the FAA engine certification guidelines can be found here. The FAA does not really care how much oil you burn so long as you specify it in the documentation and the installation can provide enough to safely run the engine with some margin on top of that.
The engine requirements for oil quantities and temperatures are established by the engine manufacturer and may be found on the Type Certification Data Sheet or in the engine installation manual. The airplane installation must not cause the engine limits to be exceeded under normal operations.
Paragraph 23.1011(c) requires that, “The usable oil tank capacity may not be less than the product of the endurance of the airplane under critical operating conditions and the maximum oil consumption of the engine under the same conditions, plus a suitable margin to ensure adequate circulation and cooling.” In other words, there needs to be enough oil (usable supply) to allow the engine to consume the usable fuel. This should be substantiated by a quantitative analysis. In addition, a suitable oil quantity margin for system circulation is necessary for all engine installations. The oil system should be capable of maintaining the engine within its operating limitations (i.e., oil temperature with the minimum oil quantity provided for circulation). Cooling tests do not need to be performed with a low usable oil supply provided the oil is properly cooled at all oil levels.
(To avoid copying all the text here) The document explains how to calculate these numbers as well under Specific Oil Consumption (SOC) and further under Single-engine Installations/Multiengine Installations. The content of Paragraph 23.1011(d) as well as Paragraph 23.1011(e) discuss feeding and pumping the oil around as needed.
Yes. Usually there is an oil consumption maximum published as an operating limitation. Which can be surprisingly high.
The GE CF-34 used on Embraers and RJs allows up to 189 cc/hr or about a fifth of a quart per hour.
The Lycoming O-290 4 cyl piston engine in my plane allows up to a quart in 2.5 hours (!).