Originally Posted by suzbmwhnd
Always drive in the highest gear, 5th if possible and lowest RPM, without lugging the engine for best fuel econony, environmental, pollution, safety, engine perservation and wear. PERIOD!
In my opinion, you are NOT saving fuel, and certainly not preserving the engine! The LT engine fuel efficiency range is certainly not when you have far higher throttle openings to get the same power to the drivetrain than you would in a lower gear. Anything below 3,000 rpm is not being kind to this engine at all. Crank and rod bearings work better when the surface speed where the crank journal meets the bearing surface is rather high, creating the "shear" pressure in the oil film necessary to insure the two surfaces never meet.
In large V-twins where RPM is never very high, the bearing journals are much larger in diameter to acheive a decent oil shear surface speed at lower RPM. The bearing journals on most high rpm performance engines are kept as small as possible to still be strong enough to handle the forces involved. If too large, the oil shear forces grow to a level at high RPM that can detract from the power produced. This engineering is quite involved, and a LOT of testing is done to produce the configurations that will deliver the best performance/reliability over the range of power the engine is designed for. Running either greatly above OR below the design range is counterproductive, in power, economy, AND reliablility. If you always keep the RPM low, you are likely reducing the bearing life of the engine. High throttle openings at low RPM can be more damaging to an engine than high RPM.
I tried to never let my LT drop below 3,000 RPM, and normally kept it between 3,500 and 7,000, and when just cruising around shifted around 4,500-5000, so that it did not drop below 3,000-3,500 after the shift.
Have you never experienced the power band of the engine above 5,500? That is where the fat lady really loves to sing.