15W40 vs 20W50

Nothing "wrong" with that, but it's more difficult to find and more expensive than T4, which I find puzzling that the OP states it's "hard to find".

T4 has been on the shelf at WM, RK and other parts stores without fail in my area. 10w40 MA is pretty much a motor-sports specific lube, where 15w-40 has a MUCH wider market base due to diesel applications, obviously. In my area, it's just the opposite; 10w-40 MA is nearly non-existent except at motor-sports retailers, and it's very expensive. T4 is everywhere and about $14 a gallon; half of what 10w-40 costs.
I've learned that "Wet Clutch" Motocycles need to have Cycle Specific Oil. A rider may not notice the slipping riding solo but once my wife got on (300lbs Total=Her & I both) The clutch started Slipping.

To the OP... Whatever weight you decide just get the cycle oil with the correct anti slip recipe for wet clutches.
 
I've learned that "Wet Clutch" Motocycles need to have Cycle Specific Oil. A rider may not notice the slipping riding solo but once my wife got on (300lbs Total=Her & I both) The clutch started Slipping.

To the OP... Whatever weight you decide just get the cycle oil with the correct anti slip recipe for wet clutches.
Someone may argue that one…and I‘m afraid he may be right !
 
Time for all those clutch plate wear/glaze and clutch adjustment cut & pastes. 😄
 
Whose Idea?. Just about every motorcycle mfgr says to use either their specific oil, or an acceptable equivalent. Kawasaki for instance, says to use an oil that has the JASO ma 1, or ma2 rating. The API equivalent has at least a SL rating. The purpose is for best clutch operation of the clutch. And to never use any oil that states it's " resource conserving" , that might cause clutch slipping. Those oils are usually a lighter grade oil like, 0w20 or the like. Like I've said before, you don't HAVE to use the mfgr's brand of oil, but you won't go wrong following their spec requirements.,,
 
The idea is that car oil is perfect fine for motorcycle clutches, including energy conserving oils.
The holy trinity of science is 1)Reason 2)Observation 3)Experience...
employing those tools we observe that the primary cause clutch slip
are high mileage... mileage is the constant among all of the clutches
that begin to slip... oil choice whether JASO approved or not is not a
constant... High mileage is the constant where all clutches begin to
loose grip due to normal glazing and contaminates that build up over use..

JASO has approved 1,537 oils as of Dec 2019 which covers virtually
everything on the market including 0w oils that would qualify as
Energy Conserving... That is because Energy Conserving is not
additive... its an API mileage test that this "oil MAY result is an
overall saving of fuel in the vehicle fleet as a whole" there is
nothing in the oil to defeat a wet clutch...

JASO approve list examples...

234 0w30 Energy Release SN 4T Jaso MA
238 0w30 Energy Release SN 4T Jaso MA
242 0w40 Energy Release SN 4T Jaso MA
243 0w40 Energy Release SN 4T Jaso MA2
244 0w50 Energy Release SN 4T Jaso MA2

389 0w30 Honda Ultra G4 Jaso MA
387 0w30 Honda Ultra G4 Jaso MA
401 0w30 Pro Honda HP4 Jaso MA

If you wish high mileage clutch life then you have to invest is some
good old sweat equity... because at the first sign of slip it doesn't
automatically mean your clutch is tired and worn out or that your
clutch plates are wore too thin because you can Mic them to
determine serviceability and within the factory specifications...

Under scrutiny you'll find that your slip was due to normal
glazing and contaminates...

Deglazing clutch plates ain't nothing new... no sir... back in the 70s
it use to be part of every savvy rider's maintenance plan... and for
some reason that all change during the 90s... why fix what you can buy
new is the what you hear now a days... but if your interested in
making your clutch bite good as new then roll up your sleeves and read
on... i

Inspect the friction plates for glazing... make sure you have plenty
of material to work with... your shop manual states clutch thickness
in thousands of an inch or mm...

First removed the contaminants with Acetone... pick a hard surface to lay
over a 600 grit black dry emery paper... rotate the clutch plate in a
circle... you're just busting the glaze... don't get carried away
remove too much material... You should end up with a friction plate
looks dull like a new one as opposed to a shinny glazed one... recheck
thickness...

gallery_3131_51_129667.jpg



Next check the pressure plates for bluing caused by localized heat...
make sure they are not warped... consult the manual for a thickness
range... now removed the contaminants with Acetone and wire wheeled
them to erased the blue and also to generally scuff up the surface...
you should end up with a dull surface free of Blue marks...

PressurePlates2.jpg.4d1e496dbcbcbb383730a9ab807432c9.jpg
 
The holy trinity of science is 1)Reason 2)Observation 3)Experience...
employing those tools we observe that the primary cause clutch slip
are high mileage... mileage is the constant among all of the clutches
that begin to slip... oil choice whether JASO approved or not is not a
constant... High mileage is the constant where all clutches begin to
loose grip due to normal glazing and contaminates that build up over use..
So where are the measurements (which you always ask for when the shifting quality discussions come up) that shows that a non JASO MA/MA1/MA2 oil doesn't slip any more than a JASO rated oil on the official friction test machine that is used to determine if the oil meets the JASO friction specifications or not?

Wouldn't "Reason, Observation and Experience" come into play when people riding a bike they have ridden 1000s of miles experience a difference in shift quality right after an oil change?
 
🍿🥤 Pulling up a chair...

In the meantime, it must be "Reason, Observation and Experience" that says non-JASO doesn't slip, because I don't see a test out there showing empirical data.

But wait, "Reason, Observation and Experience" are what lead to ascertaining shift feel. A human using "reason" by "observing" with their senses that their "experience" is real when there is a perceptible change.

ROTFLMAO
 
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So where are the measurements (which you always ask for when the shifting quality discussions come up) that shows that a non JASO MA/MA1/MA2 oil doesn't slip any more than a JASO rated oil on the official friction test machine that is used to determine if the oil meets the JASO friction specifications or not?
+1
It definitely comes across as cherry picking when one approaches clutch wear unquantified, but want to approach shift quality quantified.
 
Wouldn't "Reason, Observation and Experience" come into play when people riding a bike they have ridden 1000s of miles experience a difference in shift quality right after an oil change?
Yes... calling "Reason, Observation and Experience" into play means TESTING whether a rider experienced a difference or a placebo effect... but there is no test by either API or SAE or JASO...
 
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Yes... calling "Reason, Observation and Experience" into play means TESTING whether a rider experience a difference or a placebo effect... but there is no test by either API or SAE or JASO...
Nope ... plenty of "Reason, Observation and Experience" can be had with zero "testing" - simply by rider reason, observation and experience.

There certainly is a test standard with measurement limits for the friction level of oil in order to meet JASO wet clutch use specifications.
 
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🍿🥤 Pulling up a chair...

In the meantime, it must be "Reason, Observation and Experience" that says non-JASO doesn't slip, because I don't see a test out there showing empirical data.
Yep, he's using his "Reason, Observation and Experience" to say that non JASO rate oil doesn't cause any clutch slip at all. All the human senses seem to only work for him when it comes to clutch slip, but not when it comes to shifting quality ... seems like a double standard. 😄

Yet, he has not tested these non JASO rated oils tested per the formal friction test procedure to determine they work in a wet clutch just as well or better than a JASO rated oil.
 
Ref post #28. A worn out clutch with glazed fiber plates and blued steel plates, even if the clutch is adjusted perfectly, is more the result of an abused clutch (ie, way too much slipping by the rider) and/or an oil that may be allowing some slippage that eventually gets worse as time goes on. It could even just be slight slippage that isn't clearly apparent to the rider. If clutch slippage starts become very noticeable (with a perfectly adjusted clutch), then it's all down hill to ultimate death of the clutch. A slipping clutch only wears and slips more, it never heals itself and gets better ... unless it truly was the oil's fault and it's caught early and corrected with an oil change that doesn't cause clutch slip.

Also realize that not all clutches are designed the same or perform the same. An oil that slips in clutch A and B may not slip in clutch C or D. This is basically one reason that JASO came up with their oil friction spec for wet clutch use. A weak clutch is going to slip the most in high gear with max HP going through it. You will not detect clutch slip in lower gears and low throttle openings. If you are not going wild with high speed runs in high gear at WOT much, then you will most likely not have any clutch slip, even if not using a JASO rated oil. There are a lot of variables involved.
 
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Zero test means plenty of WAG (Wild Arse Guessing)
You mean just like the theory that clutch slippage never occurs with non-JASO rated oil because it's only based on "Reason, Observation and Experience" of the bike rider instead of test measurements like JASO requires to be JASO wet clutch rated. 😄
 
You mean just like the theory that clutch slippage never occurs with non-JASO rated oil because it's only based on "Reason, Observation and Experience" of the bike rider instead of test measurements like JASO requires to be JASO wet clutch rated. 😄

BLS, which way are you going to have it, because you can't have it both ways.
 
You mean just like the theory that clutch slippage never occurs with non-JASO rated oil because it's only based on "Reason, Observation and Experience" of the bike rider instead of test measurements like JASO requires to be JASO wet clutch rated. 😄
I mean JASO is not much help when it comes to our clutch...

Quote RDMgr
"JASO does not test oils. They register oils based on manufacturer
data and site. Most of the data is generated by additive package
manufacturers. The system is just for registration. They hate any term
that implies their approval such as “certified by”

JASO has approved 1,537 oils as of Dec 2019 which covers virtually
everything on the market... From 0w30 Energy Release to mono grades...
from Auto to Cycle oils and yet no oil has ever been listed by JASO for defeating
a wet clutch...

JASO approve list examples...

234 0w30 Energy Release SN 4T Jaso MA
238 0w30 Energy Release SN 4T Jaso MA
242 0w40 Energy Release SN 4T Jaso MA
243 0w40 Energy Release SN 4T Jaso MA2
244 0w50 Energy Release SN 4T Jaso MA2

389 0w30 Honda Ultra G4 Jaso MA
387 0w30 Honda Ultra G4 Jaso MA
401 0w30 Pro Honda HP4 Jaso MA

So no oil is currently JASO listed to be the cause of wet clutch slip... fact is
high mileage not our oil is the observed cause of a clutch loosing its grip...


full-45634-44977-jaso2.jpg
 
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I mean JASO is not much help when it comes to our clutch...

Quote RDMgr
"JASO does not test oils. They register oils based on manufacturer
data and site. Most of the data is generated by additive package
manufacturers. The system is just for registration. They hate any term
that implies their approval such as “certified by”

JASO has approved 1,537 oils as of Dec 2019 which covers virtually
everything on the market... From 0w30 Energy Release to mono grades...
from Auto to Cycle oils and yet no oil has ever been listed by JASO for defeating
a wet clutch...

JASO approve list examples...

234 0w30 Energy Release SN 4T Jaso MA
238 0w30 Energy Release SN 4T Jaso MA
242 0w40 Energy Release SN 4T Jaso MA
243 0w40 Energy Release SN 4T Jaso MA2
244 0w50 Energy Release SN 4T Jaso MA2

389 0w30 Honda Ultra G4 Jaso MA
387 0w30 Honda Ultra G4 Jaso MA
401 0w30 Pro Honda HP4 Jaso MA

So no oil is currently JASO listed to be the cause of wet clutch slip... fact is
high mileage not our oil is the observed cause of a clutch loosing its grip...


full-45634-44977-jaso2.jpg
Yes, I know all about this information in your repeated postings. Have you actually read all the JASO documents about the process to have an oil registeted by JASO? The links to the documents have been posted many times in this forum.

The friction level testing is suppose to be done per an official test standard/procedures by the company (or they have it done by an appropriate certified test lab with the specified test equipment) who wants to register the oil with JASO. An oil company just can't call up JASO and say "Hey, our oil meets the JASO friction test specs you call out, so register our oil and here's some cash". It's a bit more formal than that. JASO will not register without verified test data done per their test requirements.
 
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