Oil issues with the RB26DETT have been well documented, but as always,
Platinum has the solution.

Platinum has been supplying smaller oil restrictor for the RB26s top end.
Extensive R & D over the last 10 years have proven they are a reliable modification, one example is a tested drag car that did prove that during one
quarter-mile run an RB can spit out 4L of oil from the rocker covers into
the catch can. Furthermore, 90-percent of that accumulative volume waste is a top
end thats over-oiled, let alone the oil that actually makes it back to the
sump.

There is an argument for valve train being cooled, and too much oil does not hurt, but there is sufficient oil in the valve train system, and although too much oil does not hurt the valve train the catch can will fill, and you have less oil in your sump, you only need to lose oil pressure for a split second to detrimentally damage a bottom end.

The only oil source to the top end is a 1x2mm restrictor, up until now
commonly replaced by the Tomei 1.55 restrictor, which can still be way too
big. Thankfully, Platinum has more proactive 1.5mm, 1.3mm and 1.1mm and now .9mm (we have tested down to .7 with acceptable results thus far

Options available perfectly matched to your set-up. Also available are
blanking plugs to be used in an RB30 given the second hole has to be blocked
regardless to meet with an RB25/26 head.

Put simply, whether you return to the sump or not, there is too much oil up
top on an RB26, with way too many band-aid solutions on the market. Fixing
the issue itself is key, which is why the widely used Platinum restrictor is a must.

Oil pressure remains constant