looking for opinions

[brave sir robin]

I have a 98 Honda Superhawk. For those that are not familiar its a sportbike with a carbureted liquid cooled low compression (9.4-1 regular unleaded ftw!!) 996cc v-twin. It makes around a hundred horsepower. It has two small side mounted radiators that seem to barely be able to keep the darn thing cool when ambient gets above 85 or so.
I ride year round (on pace for about 18k miles this year) in Sacramento California and see temperatures from the 20's in winter all the way to the 100's in the summer. The manual calls for 10w-40 but I noticed some consumption (1qt 700 miles )with GN4 so I Auto rx'd it with 5w-40 Rotella to see if it would help. Almost no consumption for the 1500 mile cleaning phase but noticed shift feel got wonky after about 300 miles. I read some posts by Sunruh and rinsed with 15w-40 Rotella but immediatly started noticing consumption is back at around the same rate. So with the idea that it was temperature related and not blow by I filled my precious with Mobil 1 15w-50. So far no consumption in the 600 miles since and shift feel is like butter.....however the engine feels a little sluggish.
I would prefer to have a thinner oil that would be able stay in grade but be able to stand up to the high temps Im apparently experiencing. My plan is to go 2qts GC and 2 qts 15w-50 does that sound like a good idea? thanks

 

[KernelK]

No, I do not think it is a good idea. You have been happy with the shift feel and oil consumption so far. The gear driven cams and shared engine/ gearbox lubricant will quickly adjust your viscosity to the thinner side. It constantly amazes me how board members can feel a 1-2 horsepower difference caused by a few cSt difference in viscosity. Your hot running V-twin coupled with high ambient temperatures make the M1 15w-50 a natural if you do not see the need for a motorcycle specific oil.

If I were to cut this oil, I would be inclined to stay in the Mobil synthetic family. I had good luck with M1 15w-50 and 5w-40 turbodiesel oil at 2 and 2 in my RC51, but in much cooler Pa. temps.

Stick with the 15w-50 if it is working.

 

[ccdhowell]

I believe you are on the right path with Mobil One. You might try Mobil One V-Twin; it is essentially a 15w50 oil with all the proper adds, your bike will love it, I am certain.

 

[Ken2]

So mix up half Mobil 1 Racing 4T 10W-40 and half Mobil 1 V-Twin 20W-50.

Have you ever use a heavy duty cooling system cleanser in your engine? You might try that. Get it at an auto parts store and figure out how much to use in a bike instead of the whole thing that's sized for a car.

Are the radiators clean on the air side? Packed with bugs and dirt? Hose and blow them clean.

Renew the thermostat. They get sluggish and yours might not be opening fully. If you aren't in freezing winter weather in storage, don't use antifreeze (or drain the cooling system in winter). Use distilled water and Red Line Water Wetter or a similar product. It'll cool better.