Valvoline SynPower 75w90 gear lube
Club Member
Joined: Feb 2007
Posts: 16,320
Likes: 306
From: Boynton Beach, FloriDuh
Strange though, because I've been running synthetic gear oil in my primary/tranny for 75,000+ miles and I don't have any clutch slippage.
The fact that it's synthetic has nothing to do with clutch slippage. Any oil, fossil or synthetic, that contains moderate to high levels of a friction modifier, can cause wet clutch slippage, but it has nothing to do with whether or not it's synthetic.
Cruiser
Joined: Jul 2011
Posts: 194
Likes: 2
From: South West Missouri
I use synthetic in my primary/tranny ....no slippage here. Synthetic motorcycle oils are NOT the same as car synthetic oils. Car synthetic oil has friction modifiers that will cause slippage. Synthetic oil made for wet motorcycle cluths is just fine.
Stellar HDF Member
Joined: Aug 2009
Posts: 3,212
Likes: 212
There is a rating system used by some oils called JASO-MA and JASO-MA II (It started in Japan for use in their engines) that designates something as approved for wet clutch use. This is ideal as it is designed for wet clutch and means you are a-ok, but not having the JASO-MA rating isn't a disqualifier either.
The biggest thing, like CHarley said, is friction modifiers. These are specific additives that reduce engine wear, but will cause slippage in the clutch (important if you use a single-sump system). Since harley uses multiple sumps, it is ok to use different oil for your engine, tranny and primary designed for those purposes.
Personally, I use Mobile 1 V-Twin in both sumps. This is not to start a debate, just so you get an idea of what I use.
tl;dr Just make sure it doesn't have hi levels of friction modifiers or molybdenum (used in the industry as "Moly") in it. This will cause problems with your clutch eventually. If it says JASO-MA(2) approved it is ok.
The biggest thing, like CHarley said, is friction modifiers. These are specific additives that reduce engine wear, but will cause slippage in the clutch (important if you use a single-sump system). Since harley uses multiple sumps, it is ok to use different oil for your engine, tranny and primary designed for those purposes.
Personally, I use Mobile 1 V-Twin in both sumps. This is not to start a debate, just so you get an idea of what I use.
tl;dr Just make sure it doesn't have hi levels of friction modifiers or molybdenum (used in the industry as "Moly") in it. This will cause problems with your clutch eventually. If it says JASO-MA(2) approved it is ok.
Cruiser
Joined: Jun 2010
Posts: 143
Likes: 1
From: Yuma AZ
Oh Really, and I suppose synthetic also causes bearing skate as well..
Strange though, because I've been running synthetic gear oil in my primary/tranny for 75,000+ miles and I don't have any clutch slippage.
The fact that it's synthetic has nothing to do with clutch slippage. Any oil, fossil or synthetic, that contains moderate to high levels of a friction modifier, can cause wet clutch slippage, but it has nothing to do with whether or not it's synthetic.
Strange though, because I've been running synthetic gear oil in my primary/tranny for 75,000+ miles and I don't have any clutch slippage.
The fact that it's synthetic has nothing to do with clutch slippage. Any oil, fossil or synthetic, that contains moderate to high levels of a friction modifier, can cause wet clutch slippage, but it has nothing to do with whether or not it's synthetic.
Road Captain
Joined: Oct 2010
Posts: 535
Likes: 2
From: Saint Johns, FL
Well after checking all their web sites FAQs I do not see where any of those manufacturers recommend any oil, or against synthetic. Please provide the links to this information.
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Cruiser
Joined: Jun 2010
Posts: 143
Likes: 1
From: Yuma AZ
Their instructions when u buy them....doesnt matter im not gona go through the trouble of scanning them as I really dont care what anyone thinks as my bike operates perfectly and puts all 126 horses to the tire. I was tryin to help as no one else had replied.
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Road Captain
Joined: Oct 2010
Posts: 535
Likes: 2
From: Saint Johns, FL
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