So basically the oil pan gasket was replaced, and I believe for 2 years if the car was driven with good oil and long trip should not have much down to none sludge inside the pan..No, sump gasket was replaced two years ago; this might explain the high silicon.
But, when the gasket was replaced did you guys use Silicon with the new gasket ? If yes, this will explain the hi silicon #.
When you put the gasket and torque the bolts the silicon goes inside the oil pan and I then the Oil is absolute chemical that dissolve anything it in time...The Oil is constant in touch with the silicon and dissolve enough to show in the lab analyst...
I usually never ever put silicon on oil pan, neither when assemble cyl head on in touch with front side of the timing chain cover but on the cam tray I use silicon. I use diff liquid Permatex product that is very strong and when it make few heat cycles becomes like melted brown sugar...
I have noticed the Aluminum is 5 compare to mine engine with more miles is 1 ! So definitely a lot more Piston ware...Is the car have big piston slack in the cold morning start ?
Hear is how I extend my engine life with a lot ! I will target 500k miles on my daily...
On my E24 M6 because its a Daily driver and I enjoy it on daily base ~100miles-160km for that reason shortly when I got my car years ago I did swap large case 2.93 LSD diff form E23 745i for better fuel economy and less revs. As well I have about 100 pounds in reduction from the car. I have changed my transmission with G260 3.82 (1), 2.20 (2), 1.40 (3), 1.00 (4), .81 (5)with shorter gear ratios vs G280 3.51 (1), 2.08 (2), 1.35 (3), 1.00 (4), .81 (5) and also about 10 pounds lighter.
The result is on freeway on 5th gear the engine goes with 140km/h with only ~26000rpm/s versus 120km/h at ~3100rpm/s with 3.91LSD
This is one of the reasons my engine S38-B35 does not touch a Drop of oil in between changes. Ones in a while I do run against E46 M3 to clean up the system.
The acceleration is not that bad from rolling only. I did many time rolling pull against 3,6 and the old Avus Blue 3.8 and I was able to walk with few cars length. But the max speed it will is about 245-250km/h because the gearing is turning too heavy and long but then hear we dont have the chance to drive top speed as on the autobahn in EU.
I believe this is a big part of long lasting engine.
The Euro M635CSi and E28 M5 comes with 3.73LSD little longer than 3.91 for US.