Water cooled bike and 5w-30 Syn oil?

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Any reason why a water cooled bike couldn't just use a 5w30 instead of a 40 weight? Would the lighter oil possibly yield better power and mpg?
 
does your bike have a shared sump for engine and trans ,

I run 5W40 Rotella in my gold wing

30 might sheer down to real thin with the oil running through the trans and clutch

MPG"s?? I never cared my bike is fun time not worried about mpg's bring on spring to start the riding season
 
Does this bike share a sump with the transmission? Motorcycles and similar motors tend to be pretty hard on oil and shear them down pretty quick.
 
The water cooled bikes I've owned have all run HOTTER than the air-cooled ones. Combine this with a shared sump and the 40wt was more than justified.
 
While I don't disagree with the concerns about shear, it's interesting to note that Honda has recommended 10W-30 for many of their bikes for a good number of years now.
 
mine has been 10-40 by the owners man,,, i went to rotells t6 3 years ago not an issue with clutch or tranny runs like a champ......

quiet as a church mouse
 
Originally Posted By: jeff78
While I don't disagree with the concerns about shear, it's interesting to note that Honda has recommended 10W-30 for many of their bikes for a good number of years now.


Yep. My Honda NC750 is spec'd for 10w30. I've also run it on 5w30, and it's currently using a 10w40. Honestly, not a bit of difference between them in power or economy, and it's a pretty underpowered bike, so I'd notice any extra HP. If anything, the 10w40 gives a smoother gear change.
 
Horsepower differences are there but quite small in this report:
http://www.eatonbalancing.com/2015/02/01/oil-viscosity-and-its-effect-on-engine-power/

It's an automotive V8, but still might apply. I wouldn't choose an oil grade for my bike to increase power.

I've been using 10W30 in my shared sump Honda because it's the only recommended grade. But when I was preparing to depart on a roadtrip last September and it was 110-111F, concerns about my gearbox health operating in temps that hot with oil that thin were one factor in my decision to switch bikes--the bike I took was running 15W50, and FWIW reported an ambient temp as high as 116F during the 1st leg of the trip. I was glad I didn't take the Honda. I can hardly wrap my mind around 10W30 protecting the gearbox in normal temperatures, but still I had been following Honda's recommendation.

I think that Honda will be getting 10W40 next oil change. Motul 5100 probably because I got a gallon on sale recently, though I have almost enough Mobil 1 4T in the garage, and I think that lasts longer.
 
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Originally Posted By: Linctex
Super Tech and Traveler 15W-40 went for 84,000 miles in my 1999 Suzuki Marauder!

That's a long OCI!
 
Originally Posted By: ZZman
Any reason why a water cooled bike couldn't just use a 5w30 instead of a 40 weight? Would the lighter oil possibly yield better power and mpg?


Yes, not to be funny but the manufacturer knows why way better then us. :eek:)

But serious, coolant temperature is not as relative to oil temperature as people think.
If your coolant is 220 degrees your oil can easily be 250.
All engines different but the manufacturer knows what is best, also why I dont know of many bike manufacturers that recommend a 5w/.. oil.

Warm weather riding I always ran 20w50 in my water cooled Vstar 1300, much better shifting once the oil got hot. Winter I would run 15w40.
The lowest viscosity recommended oil for that bike is 10/40, its for a reason.
 
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Isn't all 5w30 labeled as energy conserving? Every bike (wet clutch) I have seen said to avoid energy conserving oils.
 
Don't know about the 5W30, but if you want to go for broke, Red Line's 0W20 is frictionally compatible with the JASO MA spec. (-;
 
I did a search, but I can't find a Penrite 5w30 that meets JASO MA. I am not saying that you are mistaken, I just wanted to read up on it but can't find anything.
 
I don't have the container anymore, as it was a couple of years ago, however I believe it was from their HPR range. Penrite have redone a lot of their range recently, the particular oil I used may not even be available these days.
 
Originally Posted By: ironman_gq
Does this bike share a sump with the transmission? Motorcycles and similar motors tend to be pretty hard on oil and shear them down pretty quick.


Yes it does. It is interesting though that my buddy has owned several Honda Goldwings. He has always used regular Mobil 1 5-30 in them.
 
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my buddy has owned several Honda Goldwings. He has always used regular Mobil 1 5-30 in them.


The recent and current Gold Wings sepc 5W-30. the GW
and other touring bikes are closer to autos duty wise.
Not a lot of aggressive riding or speed shifting.
I say that though many Wing riders still use diesel oil.
 
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