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Discussion Starter · #1 ·
A friend of mine changed the oil of his VN800 with 10W40 half synthetic motorcycle oil, now he's complaining about a slipping clutch.
Although I'm not an engine expert, it didn't make sense to me.
How could he go wrong with half synthetic oil?
Opinions please..
 

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Needs More Cowbell
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He didn't.
The 800's clutch springs are crap anyway, probably the new oil just made the problem noticable I'm guessing. I'm sure it was already slipping in 4th/5th gear.
 

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Replace the clutch springs with some that are 15-20% over spec. They're cheap and save wear on the clutch plates.
 

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Nobody Home
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How could he go wrong with half synthetic oil?
The problem is not synthetic oil, though it is frequently blamed. It's the "friction modifiers" added to many oils. They show up by making already marginal (common, so the lever effort won't offend the hand strength challenged) clutches slip.
 

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My guess would be he bought oil with the "energy saving" seal on it. The detergents in that oil are made for cars to help with lubrication, but they can cause damage to clutches and transmissions on bikes. That is the one thing to stay away from with oil really. Other than that, rusty could very well be on the mark. I haven't heard anyone say that oil has caused the problem in real life before, but I have read that in several owners manuals including the one for my bike and my wife's rebel.

Maybe have him drain it and put oil in that doesn't say that on the seal. I use half synth valvoline in my bike and it seems to work great. Something like $4 a qt.
 

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Discussion Starter · #7 ·
I'll ask him more about the oil.
He replied that the oil has no additives, like friction modifiers etc.
He also used this oil without problems for other bikes like a Suzuki GSXR.
 

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My experience has been that different bikes like different oils. What works in one doesn't mean it works in all. I had a 1500 Classic that hated Mobil 1 tho others swear by it. I had an 800B that hated Rotella tho others swear by it. Others hate Valvoline Full Syn but my Yami loves it. My $.02 is to tell him to dump the oil and try something else.
 

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My experience has been that different bikes like different oils.
In what respect? Clutch performance? There's one thing that seems true, if you uprade the clutch with Barnett friction plates and spring(s) the oil sensitivity goes away. Does that tell you anything about what the problem really is?
 

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I agree rbentnail,i switched from kawi oil to amsoil 10w-40 synthetic and my clutch didn't like it at all.so i changed it to royal purple 10w-40 synthetic no complaints now.i guess it made my clutch springs stronger.
 

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VN 900 Classtom
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Tell him castrol evo works pretty well at half the price of the top guys. I frankly can't tell the difference from one to the other when in the bike. I know numbers tell a different story but I go by how different a machine performs.
 

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Discussion Starter · #13 ·
Got some answer of my friend.

He used:
MPM International Oil Company

MPM Motorcycle oil
Semi Synthetic 4 stroke
10W40
Meets the requirements of:
JASO MA
ACEA A3
API SG

Personally I have never used this brand, but there are quite some people here who use it.
I believe the JASO and ACEA codes are non-additive or non friction modifier.
He bought this bike just 2 months ago cheap and it hasn't seen much oilchanges.
Now, 3 days after the oilchange, he saw that the new oil was already black again.
Can you imagine..
 

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I agree rbentnail,i switched from kawi oil to amsoil 10w-40 synthetic and my clutch didn't like it at all.so i changed it to royal purple 10w-40 synthetic no complaints now.i guess it made my clutch springs stronger.
No. You just found an oil your friction plates and wimpy spring(s) would tolerate.
 

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OK maybe (actually confirmed) im just an Dumb azz but I don't get the wimpy clutch stuff. A cruiser is not a sport bike and thus does not need the same clutching power (kinda like why Darkside tire works great for us). al that would happen if I increase the spring power in the clutching system is my hand would cramp when I am slipping the clutch for 5-10 min solid going through a military security fence to get to work. You can talk about it being built for weak hands or you can try clutching for just a min staight and then you might more appropriatly appreciate the light pull we have.
 

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A cruiser is not a sport bike and thus does not need the same clutching power
The number of threads/posts about slipping clutches and the search for the "magic oil" that makes them not slip would seem to dispute that.

if I increase the spring power in the clutching system is my hand would cramp
I guess you're the reason for wimpy clutch springs. I comfortably work the clutch with two fingers on the lever.
 
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