The Manual recommends 10/40 10/50 20/40 20/50.
So I guess the 10 range is meant for cooler climates with slower warm ups, and the 20 range is meant for warmer morning starts, and the 40 and 50 top figures are meant for holding viscosity at operating temperatures.
It has been long known that too heavy oil is harder to circulate cold, and gives rise to premature engine wear factors. The high end figures of 40 to 50 weight oil, I guess again are for people who run harder and hotter, or alternately for engines that have a good degree of wear.
The factory sets the run temperature of the engine oil to 194 F, and the water temp thermostat at 174 F to 185 F from memory, so the 10 weight difference between the two low end recommended viscosity's 10 and 20 base, and the 10 weight difference high end 40 and 50 top weight.
Out of all this,does this mean that at some point the 40 weight is going to thin too much at full temperature, needing heavier oil or a cooler? I also wonder about heat transfer comparitivly between heavier and lighter oil. I also find it interesting that hydraulics run light oil is this for heat or some other reason?
I have 10/50 Penrite in my bike,and have noticed if I leave it on the side stand over night, it will puff a bit of white to grey smoke till warm. left on the centre stand ,no smoke. Perhaps it's a worn guide and or I should have used a 20/50 oil,with a bit more body cold. What's your thinking?
Who walks into the Lions Den, and comes out alive?
12 inch apes
1986 A3 series 750
Slash cut stainless mufflers
170 rear tyre
Custom cyane blue paint, wheels included
Relocated regulator rectifier
Stainless washable oil filter
Six pack rack
LED indicators and flasher unit.
Oil pressure hot at 1000 rpm 20 psi, 4000 rpm 60 psi
Shows 67000 kms
Jets 38 idle Mains 120 changed to 40 idle 135 main.
Last edited by Big Nick; 03-07-2014 at 03:16 AM.
Reason: Added comment.