10w-30 or 10w-40 for 04' AR230?

[Shannon]

I have owned 2 M3's and now an Audi S4 and SQ5.. I have always used the Castrol European 0w40 and it has never let me down. The 05 e46 M3 had 78000 hard miles when I let her go. I always changed at 5K and it never ever used any extra oil. Same with 13 S4 as they are known to use some oil. The new 17 SQ5 at 1k on it was filled with the 0w40 Castrol also.. As for my 16 AR192 after 8 hours I put the ow40 in it also. Last October I changed the oil at 28 hours and the oil still looked new. I now plan on changing every other season using the Castrol Euro for the boat. Some of my friends that have newer S4's were using Moly Lube 5w40.They both were having to add a quart at around 3k in between there 5k oil change. Not bashing Moly Lube as it is a great German oil. They both switched to castrol and the cars are not using oil. Just thought I would throw this out there as I have had really good luck with Castrol Euro ow40 and ow30. I agree with @swatski great thread discusing oil!

 

[tdonoughue]

My biggest concern was or still is Yamaha suggest for us to use 10W-40 on the MR1's HO, now the motor head in me tells me I should use a 0w-40 because these motors are high RPM motors. Last boat I owed had a mild performance 5.0 liter motor and my engine builder suggested to stick with 0w-40 motor oil due to the constant high RPM's and that motor would red line at 6,000 RPM's, and now Yamaha is suggesting to use 10W-40 on a 10,000 RPM motor!

Note that RPM on the engine is only one factor. The tolerance of the parts, the gap designed between them and the designed hydraulics of the oil dispersion mechanism all also play a role. Different engine design may call for a different oil.