Multigrade / Single grade mix.

[inspekor]

What happens to the viscosity when you mix a single grade into a multigrade? I normally run 15w40 Rotella in my '83 Goldwing, however this past week temps have been in the 100's and I would be more comfortable if I were running a 20w50. If I were to add 25% 50wt Rotella to the 15w40 or say the 5w40 Rotella synthetic the 'winter' rating would surely increase, but what would happen the viscosity at 100c? Would the viscosity modifiers in the 15w40 or 5w40 increase the brew above a 40wt being the the baseline viscosity has increased? Is it possible to brew something close to a 20w50 out of the available Rotella weights?

 

[sunruh]

rotella is pretty good stuff. no need to worry.
yeah, been a bit warm.

 

[tmorris1]

The Goldwing is liquid cooled, so it shouldn't stress the oil much at all.

 

[dwendt44]

And synthetic is very good at handling the heat.
You're doing fine.

 

[Gary in Sandy Eggo]

A 1983's a pretty old bike. Engine clearances are bound to have opened up a bit over time. If I were operating a motorcycle that old in 90F-100F+ temperature ranges on a daily basis, I be running straight automotive SAE-40. That's what I run (Pennzoil) in my 1999 Intruder (which is air/oil cooled) year round riding in temps that range from 55F-85F. It's got 23K miles on it, I do 5000-mi OCI, and the oil consumption over that 5000 miles represents about 1/8" on the dipstick (literally none). (I do preheat my engine case overnight with a shop-light before rides during the winter.)