140 is quite a bit higher viscosity than the Honda recommended 90. Do you add enough Lucas stabilizer the bring it down or am I over-thinking it?
Can I ask what brand oil and what Oil / stabilizer ratios you use?
75-140 isn't actually a 140 weight oil. It gives the protection of a 140 and flows like a 75 weight when cold.
The idea IS to thicken the oil to reduce noise. Now, it will cause an increase in parasitic power loss in the drive train but not noticeable at all.
The lucas oil additive is very thick and "clings" to the gears for very good wear protection. It will also provide some cushion to reduce noise. I used 50% OEM oil and 50% lucas on the pioneer 1000
On the P700 I used Mobil 1 75-140 and lucas additive.
I hope his helps. I never had any adverse affects. Now, my friend owns my old pioneer 700 and still drives it with the same oil in it. It's approaching 1000 miles and no problems. Also, many others have done this same thing.
Joe