I very seriously doubt that ANY Enfield is shipped with synthetic oil from the factory.
Break-in requires some friction for items to properly bed, and it's been shown that synthetic oils may be counterproductive in this regard for break-in purposes.
The proper oil for break-in would be a Dino oil which is API rated with the SL rating, or previous.
Not SM rating.
SM rated oils are the new formulations to extend the lives of catalytic converters, and lack sufficient zinc and phosphorous additives to properly lubricate solid lifters and cams during a break-in period.
Dino oil of API rating of SL or earlier, 20w-50, will get it done.
For the new UCE with hydraulic lifters, the foregoing information MAY not apply, but I have no specific information about that yet.
IMHO
Kevin is correct
# 1 - He is the head honcho at CMW, and an official channel partner ,representing REML for the U.S.
# 2 - The Factory / Principals , have to keep C.M.W. updated on technical upgrades, changes, mods etc. via service bulletins & he might be the first person to know if any changes/ mods are incporporated in U.S. spec. Enfield models.
# 3 REML still does not have the resources as huge as the Japanese biggies to invest into the latest tooling and machining technology to produce engines to
very close tolerances that might allow usage of synthetics from factory fill itself , Because - Synthetics comprise of additives that prevent frictional wear and tear & the old tech. derived engines of the Enfields, do require a little bit of wear and tear between moving parts, and that's the reason we call it a ''Bedding in /
Running in'' process and its the specific reason why an Enfieldeer is first required to drain the oils in the first couple of hundred miles & does find quite a bit of ferrous/non ferrous metal wear parts floating in the oil during the first 1 or 2 or 3 oil changes
# 4 Synthetics / Dino-Minerals oils from various brands - Is again like a mixture of base oils and additives and ''special formulations'' tried and tested to operate under varied operating / load conditions and environs, but the basics still boils down to ''lubrication''........prevent metal to metal contact or friction between moving parts
Over all (I Feel ) - As far as Royal Enfields are concerned, i am sure that synthetics are still not used as first fill lubricants