I had been using 5% Exxon 2380 for my RAM 500, but Carlos noted it developed heavy coking over time. When I got my 44 I used 3% as Wren suggested, and when asked they recomended I run my RAM500 on 3% also. Have run both on 3% turbine oil for about 100 cycles without problems. I cannot see running the 44 on 5%, because of the tiny needles, while I should think the the 54 should run as well on 3% as on 2.5%.

Finishing my last quart of 2380 and am planning next to switch to Aeroshell 500, which has the reputation of producing less carbon buildup. This is not a definitive answer, but what works for me.