What I have done all my life with brake fluid, is I buy big container of brake fluid. Every 2 years I suck out fluid in reservoir, but still keep it above level to not get air, fill, and every couple days, do it until bottle is empty. Never done a brake flush in any vehicle and I am almost 59. Never had any brake issues, other than replacing rotors/pads. I think 40k is too soon for brake flush unless you tow a lot. I do know from previous and current 5.7s and other vehicles, adding a double dose of good fuel injector cleaner in gas does make noticable difference. I use gumount/regane/etc with p.e.a, if says use 8oz for 10 gallons I use double, at same time I add Lucas fuel system cleaner at same time. I feel the Lucas adds lubrication and the pea cleaner opens up clogs in injectors. When tank hits about time to fill up again I can feel trucks smoother and had better power. The 5.7 is only engine I really can feel a big difference(have had 4, 2 Ram trucks, 1 dodge durango, 300) when using the cleaners, its noticable.