My '07 Cooper (non-S) is a bit rough at start-up, but I think it's fuel related, not oil pressure based. But if I heard THAT noise at THAT volume coming from under the bonnet I'd need to change my pampers

Since most of these posts seem to come from MCS cars, I wonder if if it's possible that when the engine is shut down the increased oil temperatures have thinned the oil to the point that less of it remains in the pipes, and more pools down in the bottom pan. This seemed to be the case with my '05 Subaru 2.5XT ltd (turbo), was a big problem for motorcycles (back in the day), and was/is a point of debate regarding viscosities. We found that thinner synthetic oils were more prone to run into the pan than the next higher viscosity petroleum oils (probably not the case today 30 years later). Theoretically, synthetic oils might have a slightly higher film strength than dinosaur lube, especially midway between oil changes as the oils begin to lose some of their additive package benefits. This was one of the biggest motivators for adding STP (anybody here old enough to remember THAT stuff? ), as it purportedly increased film strength.

To overcome the problem, electric oil pumps were added to some high performance cars and bikes to be sure there was oil pressure in the engine BEFORE the initial startup (where, as we all know, the majority of engine wear occurs).

If I experienced that symptom, though, after visiting the dealer first to record the problem and ask for a fix, I might consider trying the next higher weight oil. Whatever it is, it ain't right

Just my $.02 Good luck!

Afterthought... More of a question I guess. Is the cam chain tensioner hydraulic? Could a lack of pressure there be a contributor to the noise?

 

See above...

 

Guess that answers THAT