Advice please: Bike oils, Car oils?

[aum108]

Hi all,

I'm wondering if some of you mechanically skilled folks could please set me right on the issue of what oil to use in a (4 stroke) motorbike.

I've managed to get totally confused by all the contradictory opinions on the net, and would like to pull back and get some local wisdom.

At the moment, I have 15W40 (mineral) car oil in the bike, but at first opportunity (next payday) will be replacing it with something more suitable to the bike, which is a Yamaha XV250 Virago, v-twin air-cooled.

Currently the bike is clutch-dragging, more so when cold. The drag is enough to stall the motor sometimes when I put it out of neutral into 1st gear when cold (with clutch fully pulled in). Could this be partly or totally due to the oil?

Is car oil ALWAYS BAD for bikes? Or are there specific types of car oil to avoid?

What specifically is the danger of using (certain types of) car oil in bikes? Some folks mention "clutch damage". What are the specifics of this?

What oil is best for my Virago 250? The manuals say SAE 20W40 (warm climates) or 10W30 (cold climates). But some Virago owners reckon 10W40 is great.

Are the motorbike oils from Super Cheap Auto ok? A couple of them are less than $20/litre.

And what about mineral versus synth versus semi-synth? What should I look out for here?

Lastly, can oil choice affect fuel economy and power?

Thanks for your patience and help.

Cheers
David

[MSTRS]

Only advice I can give is use a 4T oil. Find out what Yamaha recommend as to 10/30 - 10/40 - 20/50 - whatever, and find a 4T (motorcycle only) oil that suits your budget. Do not use fully synthetic, as your Virago wasn't designed with it in mind.
Clutch drag is more likely to be caused by poor adjustment, rather than oil. Car oils tend to make m/c clutches slip.

PS - I have heard a rumour that diesel engine oils are fine in 4 stroke bikes - but can't confirm if this is so.

[blackdog]

Nah it's only a 250. Just use recycled oil outta yer deep fryer will be fine.

[FJRider]

Any oil is better than no oil ...

But .... car oils have an anti-friction agent (which sounds good) which make clutches slip. The unknowing try to adjust the clutch to stop the slipping ... which results in the clutch not releasing.

To simply replace the engine oil is not the quick fix. Clutch plates may need to be replaced. On-going clutch problems/issues if you dont.

Diesel oil has been used on older bikes ... a cheap option.

BUT dont use car oil. Things just go bad. FAST. You WONT save money using it. If you cant afford motorcycle oil, you cant afford the repair bill ...

[pritch]

This can get soooo complicated. Stick with a motorcycle specific oil in a grade recommended by the manufacturer though and it can be simple.

If the choice is 20/40 or 10/30, neither will damage the bike. The 20/40 may make the bike run a degree or two hotter, give a fraction of a horsepower less, but it might make the gear changes smoother.

The only disadvantage of a motorcycle specific oil that comes to mind is that they are not normally available at service stations, but then you hopefully won't need to make any unplanned purchases.

When you trade up to a bigger bike it could pay to revisit the question, but the simple advice would still be to use a motorcycle specific oil in the grade and weight recommended by the manufacturer.

Oh, and I'm not sure that buying the cheapest oil you can find is the best policy?

[spanner spinner]

In simple terms car oils are for cars bike oils for bikes. The big difference is that cars have separate gearboxes with there own oil so there oils are not designed to work with wet clutches or gears which cause them to break down fast and cause clutch problems when used in bikes as you have discovered. My recommendation would be a 10w40 semi synthetic motorcycle oil (i.e. motul 5100) super cheep does Castrol bike oils and will have one to suit, GPS would be my first pick.

[Woodman]

The clutch dragging when cold may well be the viscosity and not necessarily the type of oil. You are using a 15w40 which is thicker than a 10w40 at ambient temperature and so on as the oil warms up therefore when the clutch plates squeeze together the thicker oil takes a bit longer to be squeezed out between the plates causing drag. Try a 10w40 and see what happens. My old xl600 had the same symptoms when running a 15w40 until I put the 10w40 in so this was the theory I came up with rightly or wrongly.

Car vs bike oils? use bike oils as it saves way too many meaningless conversations about car vs bike oils. Interestingly Penrite state on a few of their car oils that they are also recommended for motorcycles.

[cowpoos]

In simple terms car oils are for cars bike oils for bikes.

This is the best advice....get bike Oil....its different for a reason!

[Flip]

Firstly there is no specification for bike oils. The SAE (socioety of automotive engineers) have never produced one. All the bike makers simply tell you to use a good quality car oil, I might suggest they know best.

There have not been any friction modified engine oils available for ages, the boundary lubricants polute catalitic converters.

All quality motor oils have dual petrol Sx and diesel Cx ratings. Oils after SG are "low ash" and compatible with cats from memory oils after SH are energy efficient as well.

The only issues with std automotive oils in bikes is the VI (viscosity index) addative, which looks like gorilla snot and is the stringy chemical that makes a 20 weight base stock oil behave like a 40 weight oil when itis hot (ie 20W40) is chopped up by the gear boxes in bikes. Its not shear stable. As the oil ages it thins when it is hot and the gear boxes get notchy, thats why new oil always feels better in the box and why oil change intervals will always be closer in bikes than in cars.

I am a great fan of commercial mixed fleet oils, bulk 10-20 litre packs save me money and my vehicles get more oil chages. I run the same 15W40 Valvolene mixed fleet lube in all my vehicles.

The most important thing is that the oil has a high S rating, SG is good. What the 15W40 numbers means is the oil viscosity behaves like a 15 weight oil at 40 deg C and a 40 weight oil at 100 deg C. There is fuck all diference between a 15W40 and a 20W50 one, they are both fine for use in New Zealand. All motor oils are missible in an emergency, one of the SAE requirements is that they can mix, but if you mix a 30W40 with Mobil 1 the oil you now have is no better than 30W40

Don't ever buy a oil with a flash holographic label or in some fancy bottle, you are wasting your money. Don't buy an oil that you can't get at your local service station.

Get your clutch adjusted it does not sound to me like a oil problem to me.

Read this....... http://www.dansmc.com/mc_repaircourse.htm

[cowpoos]

All the bike makers simply tell you to use a good quality car oil, I might suggest they know best.



Bull shit...why come on to a thread like this and mis inform people?? read a bike owners manual sometime!

[Flip]

Bull shit...why come on to a thread like this and mis inform people?? read a bike owners manual sometime!

Because there are oil makers and retailers out there making "specialty" lubricants, that comply with no standard or specification, charging a premium price for an untested and unproven snake oil product. They seem to have got their expensive products into the motorcycle retailers who are hocking it off to people who know no better.

Which part do you think is bull shit cow poos?

[aum108]

Thanks for the advice guys.
Well, I finally bought some Castrol 4T 10W40 semi-synth, but now the oil drain bung bolt won't budge.
Crap time of day to be lacking an 18mm socket or ring spanner! :/
Always tomorrow I guess.

[mossy1200]

supercheap has castrol for bikes or bike shops motul.Sure it 60-70 instead of 40 bucks but clutch pack costs more than the price difference.Get that bike hot drain it filter it.If that doesnt solve it order clutch gasket tilt bike and strip clean clutch keeping everything in the correct order.Maybe soak plates in the correct oil over night and reasemble.

[cowpoos]

Because there are oil makers and retailers out there making "specialty" lubricants, that comply with no standard or specification, charging a premium price for an untested and unproven snake oil product. They seem to have got their expensive products into the motorcycle retailers who are hocking it off to people who know no better.

Which part do you think is bull shit cow poos?

your conspiracy theories sound like shit to me actually...

Now let me see...would I stick oil ....designed for a engine reving say 5-6 thou RPM in my four cyclinder bike engine designed to rev 12-13 thou RPM?? no...heard about the initial excess wear on high reving single four stroke MX engines using normal bike oils??? problem was solved with specilty oils!! go figure...

don't mis inform people...but I expect you so come back and talk more shit...coz your a name calling type with ego issuses.....take soon....ciao :)

[mossy1200]

your conspiracy theories sound like shit to me actually...

Now let me see...would I stick oil ....designed for a engine reving say 5-6 thou RPM in my four cyclinder bike engine designed to rev 12-13 thou RPM?? no...heard about the initial excess wear on high reving single four stroke MX engines using normal bike oils??? problem was solved with specilty oils!! go figure...

don't mis inform people...but I expect you so come back and talk more shit...coz your a name calling type with ego issuses.....take soon....ciao :)

+1 this is his motorbike not the neighbour you dont likes weedeater that wakes you up on Sunday morning at 7am.

[Flip]

Bull shit...why come on to a thread like this and mis inform people?? read a bike owners manual sometime!

I am really interested to know what part do you think is bull shit?

I have a small model aircraft motor that revs to 20,000 rpm, it uses castor oil as lubricant.

[Kickaha]

Now let me see...would I stick oil ....designed for a engine reving say 5-6 thou RPM in my four cyclinder bike engine designed to rev 12-13 thou RPM??

I just checked 7 workshop manuals, 3 are factory manuals and 4 were Clymer/Haynes, not one of them mentions "motorcycle oils" they all say SAE10-30SE or SAE 20-50SF or whatever and only say engine oil

The Yamaha manuals of course say Yamalube which will be some other brand in their packaging but also give an alternative "engine oil"

The K5 GSXR1000 factory manual only says "Oil quality is a major contributor to your engine’s performance and life. Always select good quality engine oil. Use of APISF/SG or SH/SJ with JASO MA.Suzuki recommends the use of SAE 10W-40 engine oil"

[Flip]

My HD manual says, use a 15W40 or 20W50 oil with a CF to CI clasification,which is a diesel specification.

Even Mobil 1 has a diesel oil SAE CI rating.

[Kickaha]

Cowpoos is just grumpy because he hasn't been allowed a pie for months

[Flip]

Thanks for the advice guys.
Well, I finally bought some Castrol 4T 10W40 semi-synth, but now the oil drain bung bolt won't budge.
Crap time of day to be lacking an 18mm socket or ring spanner! :/
Always tomorrow I guess.

Castrol make a good product. Whats the Sx letters on it?

[Flip]

Cowpoos is just grumpy because he hasn't been allowed a pie for months

Ahhhhhhhhhhh.

He needs to do some thing about that?

[FJRider]

Ahhhhhhhhhhh.

He needs to do some thing about that?

A pint of 10W40 would sort his issue out ... pie's would never be an issue again ...

[pritch]

When you've read this you will know more than the guy at the bike shop...

http://www.ducatimonster.org/forums/tech/122020-motor-oil.html

[Kickaha]

A pint of 10W40 would sort his issue out ... pie's would never be an issue again ...

I hope that would be "Motorcycle oil" not just any plain old 10W40

[pritch]

Some of those manuals might be a bit old?


The Triumph Speed Triple manual makes sense to me:

Oil Specification and Grade
Triumph high performance fuel injected engines are designed to use 10W/40 or 15W/50 semi or fully synthetic motorcycle engine oil that meets specification API SH (or higher) AND JASO MA.
Do not add any chemical additives to the engine oil. The engine oil also lubricates the clutch and any additives could cause the clutch to slip.
Do not use mineral, vegetable, non-detergent oil, castor based oils or any oil not conforming to the required specification. The use of these oils may cause instant, severe engine damage.

[Kickaha]

Some of those manuals might be a bit old?

Some of the manuals I originally quoted are from the eighties but the K5 GSXR manual wasn't

[cowpoos]

I just checked 7 workshop manuals, 3 are factory manuals and 4 were Clymer/Haynes, not one of them mentions "motorcycle oils" they all say SAE10-30SE or SAE 20-50SF or whatever and only say engine oil

The Yamaha manuals of course say Yamalube which will be some other brand in their packaging but also give an alternative "engine oil"

The K5 GSXR1000 factory manual only says "Oil quality is a major contributor to your engine’s performance and life. Always select good quality engine oil. Use of APISF/SG or SH/SJ with JASO MA.Suzuki recommends the use of SAE 10W-40 engine oil"

BSA, norton, briggs and straton manuals knowing you....from the 1570's ???...I find that suzuki one interesting...every manual I've read states motorcycle oil.


My HD manual says, use a 15W40 or 20W50 oil with a CF to CI clasification,which is a diesel specification.

Even Mobil 1 has a diesel oil SAE CI rating.

Harley Davidson right?

[cowpoos]

Oil quality is a major contributor to your engine’s performance and life. Always select good quality engine oil.
Suzuki recommends the use of SUZUKI PERFORMANCE 4 MOTOR OIL or equivalent engine oil. Use of
SF/SG or SH/SJ in API with MA in JASO.
Suzuki recommends the use of SAE 10W-40 engine oil. If SAE 10W-40 engine oil is not available, select an
alternative according to the following chart.



Some of the manuals I originally quoted are from the eighties but the K5 GSXR manual wasn't

as above from the manual...Suzuki performance 4 motor oil....I can email you the manual... K5 K6 gsxr 1000...

[Woodman]

So, what is different about motorbike and car oils.?

The only thing I have ever read on a motorcycle oil pack (castrol activ 4t) is that it had some additive in it to help prevent corrosion because motorcycles spend a lot of time inactive.

I think the lines are a bit blurred between marketing and engineering.

[cowpoos]

So, what is different about motorbike and car oils.?

The only thing I have ever read on a motorcycle oil pack (castrol activ 4t) is that it had some additive in it to help prevent corrosion because motorcycles spend a lot of time inactive.

I think the lines are a bit blurred between marketing and engineering.

gearboxes,clutches,engine share same oil on bikes...much smaller oil galleries....much much finer tolerences...Higher rpm.

seriously..lots

[Woodman]

seriously..lots

Thanks, now i know.

[Coolz]

[QUOTE=cowpoos;1130252198]Oil quality is a major contributor to your engine’s performance and life. Always select good quality engine oil.
Suzuki recommends the use of SUZUKI PERFORMANCE 4 MOTOR OIL or equivalent engine oil. Use of
SF/SG or SH/SJ in API with MA in JASO.
Suzuki recommends the use of SAE 10W-40 engine oil. If SAE 10W-40 engine oil is not available, select an
alternative according to the following chart.


That is word for word what it says in my 91 Suzuki vx800 owners manual. Last oil change I used a 10-40 semi synthetic oil. My bike now has a horrendous noise coming from the gearbox which I have been told is a stuffed bearing in the bevel drive unit. This could be just wear and tear on a 70,000k engine but I have an uneasy feeling I could have caused this by changing from my normal mineral oil. I have been searching the web for information on oil and everyone seems to have a diferent and often contrary opionon. A real can of worms.

[jonbuoy]

Firstly there is no specification for bike oils. The SAE (socioety of automotive engineers) have never produced one. All the bike makers simply tell you to use a good quality car oil, I might suggest they know best.

There have not been any friction modified engine oils available for ages, the boundary lubricants polute catalitic converters.

All quality motor oils have dual petrol Sx and diesel Cx ratings. Oils after SG are "low ash" and compatible with cats from memory oils after SH are energy efficient as well.

The only issues with std automotive oils in bikes is the VI (viscosity index) addative, which looks like gorilla snot and is the stringy chemical that makes a 20 weight base stock oil behave like a 40 weight oil when itis hot (ie 20W40) is chopped up by the gear boxes in bikes. Its not shear stable. As the oil ages it thins when it is hot and the gear boxes get notchy, thats why new oil always feels better in the box and why oil change intervals will always be closer in bikes than in cars.

I am a great fan of commercial mixed fleet oils, bulk 10-20 litre packs save me money and my vehicles get more oil chages. I run the same 15W40 Valvolene mixed fleet lube in all my vehicles.

The most important thing is that the oil has a high S rating, SG is good. What the 15W40 numbers means is the oil viscosity behaves like a 15 weight oil at 40 deg C and a 40 weight oil at 100 deg C. There is fuck all diference between a 15W40 and a 20W50 one, they are both fine for use in New Zealand. All motor oils are missible in an emergency, one of the SAE requirements is that they can mix, but if you mix a 30W40 with Mobil 1 the oil you now have is no better than 30W40

Don't ever buy a oil with a flash holographic label or in some fancy bottle, you are wasting your money. Don't buy an oil that you can't get at your local service station.

Get your clutch adjusted it does not sound to me like a oil problem to me.

Read this....... http://www.dansmc.com/mc_repaircourse.htm

Not sure about there being no difference between 15W40 and 20W50, try pouring 20W50 on a cool morning - pretty gloopy stuff, visible difference to the 15W40.

[Kickaha]

Oil quality is a major contributor to your engine’s performance and life. Always select good quality engine oil.
Suzuki recommends the use of SUZUKI PERFORMANCE 4 MOTOR OIL or equivalent engine oil. Use of
SF/SG or SH/SJ in API with MA in JASO.
Suzuki recommends the use of SAE 10W-40 engine oil. If SAE 10W-40 engine oil is not available, select an
alternative according to the following chart.




as above from the manual...Suzuki performance 4 motor oil....I can email you the manual... K5 K6 gsxr 1000...

Doesn't say anything about "Motorcycle oil" in the above it says engine oil, SUZUKI PERFORMANCE 4 MOTOR OIL will just be something else rebranded

SF/SG etc can all be found on "Car Oils"

[TimeOut]

Not sure about there being no difference between 15W40 and 20W50, try pouring 20W50 on a cool morning - pretty gloopy stuff, visible difference to the 15W40.

Yep and cold starts are when most engine wear happens made even worse by those thicker when cold grades

[sinfull]

Thanks for the advice guys.
Well, I finally bought some Castrol 4T 10W40 semi-synth, but now the oil drain bung bolt won't budge.
Crap time of day to be lacking an 18mm socket or ring spanner! :/
Always tomorrow I guess.

When you get up this morning and read through the battle of oils, do so with a jar of very strong acid, take that cresent you were trying to undo your drain plug with and submerce it in said acid !

Then go back to super cheap and buy some tools for your bike !

Change your oil and adjust the clutch lever ! Dont swing on the drain plug to do it up this time, it has a crimp washer there for a reason ! There will even be a torque setting for said drain plug in a manual !

[pritch]

Some of the manuals I originally quoted are from the eighties

Well, technology has moved on exponentially since then. Back then we didn't have big screen TVs, iPods, or a whole bunch of other stuff.

In most cases synthetic oils aren't just marketing hype, although in the instances of Castrol and Shell there is a question mark. Castrol convinced a judge that their oil was "synthetic" so they could call it that. Their definition of synthetic was different to the industry standard used by Mobil, Motul, Amsoil, and others.

If you want to know the difference read that link I posted. It's a long, sometimes rambling thread, but "George" was a lubrication engineer who owned bikes and rode on the track. He knew that of which he wrote.

[MSTRS]

Thanks for the advice guys.
Well, I finally bought some Castrol 4T 10W40 semi-synth, but now the oil drain bung bolt won't budge.
Crap time of day to be lacking an 18mm socket or ring spanner! :/
Always tomorrow I guess.




Then go back to super cheap and buy some tools for your bike !

Change your oil and adjust the clutch lever ! Dont swing on the drain plug to do it up this time, it has a crimp washer there for a reason ! There will even be a torque setting for said drain plug in a manual !

Seen it before...
The sump plug is 'upside down' and inexperienced spanner wielders forget to 'turn the other way'. Therefore they are tightening that bolt!! Which is real good for the helicoil in the casing.

Car oil or bike oil? Is a car engine oil used in a car gearbox? No, I hear you say. That's good enough for me.

[Owl]

Doesn't say anything about "Motorcycle oil" in the above it says engine oil, SUZUKI PERFORMANCE 4 MOTOR OIL will just be something else rebranded

SF/SG etc can all be found on "Car Oils"

But it does say "JASO MA", which is motorcycle specific without friction modifiers. JASO-MB is motorcycle specific with friction modifiers.

[aum108]

When you get up this morning and read through the battle of oils, do so with a jar of very strong acid, take that cresent you were trying to undo your drain plug with and submerce it in said acid!
Yeah, there are places where a crescent was never meant to go. :P


Then go back to super cheap and buy some tools for your bike !A $4 17mm socket did the trick just nicely :)


Change your oil and adjust the clutch lever!Turned out it wasn't the clutch lever. After a few km with the new oil (10W40 semisynth) the clutch drag is gone.


Dont swing on the drain plug to do it up this time, it has a crimp washer there for a reason ! There will even be a torque setting for said drain plug in a manual !This is the first time I've touched the drain plug. The previous owner('s mechanic) was the one who jumped on the breaker bar doing it up last time! :eek:

[aum108]

Seen it before...
The sump plug is 'upside down' and inexperienced spanner wielders forget to 'turn the other way'. Therefore they are tightening that bolt!! Which is real good for the helicoil in the casing.

Nice... try!!! :)

Maybe I should have given it full-force clockwise. Would have led me into gaining skills into tapping new threads! :P

As it happens, I just copped out and forced it anticlockwise. One really hard pull of the wrench, a metallic 'crack' sound, and the bolt was free.

[MSTRS]

Nice... try!!! :)

Maybe I should have given it full-force clockwise. Would have led me into gaining skills into tapping new threads! :P

As it happens, I just copped out and forced it anticlockwise. One really hard pull of the wrench, a metallic 'crack' sound, and the bolt was free.

Try? Nah mate - it's true. You'd be amazed.
And that 'crack' sound followed by a bolt that turns quite freely...also more common than you'd think.

[Flip]

I found this interesting http://en.wikipedia.org/wiki/Motor_oil , espcially the comment "All the current gasoline categories (including the obsolete SH), have placed limitations on the phosphorus content for certain SAE viscosity grades (the xW-20, xW-30) due to the chemical poisoning that phosphorus has on catalytic converters. Phosphorus is a key anti-wear component in motor oil and is usually found in motor oil in the form of Zinc dithiophosphate. Each new API category has placed successively lower phosphorus and zinc limits, and thus has created a controversial issue obsolescing oils needed for older engines, especially engines with sliding (flat/cleave) tappets. API, and ILSAC, which represents most of the worlds major automobile/engine manufactures, states API SM/ILSAC GF-4 is fully backwards compatible, and it is noted that one of the engine tests required for API SM, the Sequence IVA, is a sliding tappet design to test specifically for cam wear protection. However, not everyone is in agreement with backwards compatibility, and in addition, there are special situations, such as "performance" engines or fully race built engines, where the engine protection requirements are above and beyond API/ILSAC requirements. Because of this, there are specialty oils out in the market place with higher than API allowed phosphorus levels. Most engines built before 1985 have the flat/cleave bearing style systems of construction, which is sensitive to reducing zinc and phosphorus. Example; in API SG rated oils, this was at the 1200-1300 ppm level for zincs and phosphorus, where the current SM is under 600 ppm. This reduction in anti-wear chemicals in oil has caused premature failures of camshafts and other high pressure bearings in many older automobiles and has been blamed for pre-mature failure of the oil pump drive/cam position sensor gear that is meshed with camshaft gear in some modern engines."

The JASO T904-2006 also made for interesting reading being a set of tests for wet clutch compatability, http://www.jalos.or.jp/onfile/pdf/4T_EV0604.pdf but it is an addittional test on a good quality car motor oil and not a specific motorcycle oil. This also made interesting reading http://en.wikipedia.org/wiki/Motorcycle_oil.

[Woodman]

Turned out it wasn't the clutch lever. After a few km with the new oil (10W40 semisynth) the clutch drag is gone.:

Thinking your clutch is sensitive to viscosity like my old xl as I mentioned in previous post.

My klr clutch doesn't change from using a 10w40 to a 40w70 which I used to try and fix an oil burning issue.

Getting hard to find SG or lesser grade oils now. Most brands are now bringing SN oils to the market.

[nosebleed]

When you've read this you will know more than the guy at the bike shop...

http://www.ducatimonster.org/forums/tech/122020-motor-oil.html

Thats a great read man, thanks.
Only 20 pages through atm but I've got what I need so far. Just hoping theres something more as I work towards the 60-odd mark.

[TimeOut]

I found this interesting http://en.wikipedia.org/wiki/Motor_oil , espcially the comment "All the current gasoline categories (including the obsolete SH), have placed limitations on the phosphorus content for certain SAE viscosity grades (the xW-20, xW-30) due to the chemical poisoning that phosphorus has on catalytic converters. Phosphorus is a key anti-wear component in motor oil and is usually found in motor oil in the form of Zinc dithiophosphate. Each new API category has placed successively lower phosphorus and zinc limits, and thus has created a controversial issue obsolescing oils needed for older engines, especially engines with sliding (flat/cleave) tappets. API, and ILSAC, which represents most of the worlds major automobile/engine manufactures, states API SM/ILSAC GF-4 is fully backwards compatible, and it is noted that one of the engine tests required for API SM, the Sequence IVA, is a sliding tappet design to test specifically for cam wear protection. However, not everyone is in agreement with backwards compatibility, and in addition, there are special situations, such as "performance" engines or fully race built engines, where the engine protection requirements are above and beyond API/ILSAC requirements. Because of this, there are specialty oils out in the market place with higher than API allowed phosphorus levels. Most engines built before 1985 have the flat/cleave bearing style systems of construction, which is sensitive to reducing zinc and phosphorus. Example; in API SG rated oils, this was at the 1200-1300 ppm level for zincs and phosphorus, where the current SM is under 600 ppm. This reduction in anti-wear chemicals in oil has caused premature failures of camshafts and other high pressure bearings in many older automobiles and has been blamed for pre-mature failure of the oil pump drive/cam position sensor gear that is meshed with camshaft gear in some modern engines."

The JASO T904-2006 also made for interesting reading being a set of tests for wet clutch compatability, http://www.jalos.or.jp/onfile/pdf/4T_EV0604.pdf but it is an addittional test on a good quality car motor oil and not a specific motorcycle oil. This also made interesting reading http://en.wikipedia.org/wiki/Motorcycle_oil.

I'm pretty sure moyorcycle oils are allowed higher znic levels to give better wear protection

[aum108]

So far, the 10W40 semi-synth oil is sitting nice in the XV250.
No more clutch drag whatsoever. When it's cold with engine off, and I hold the clutch in, there's no extra resistance with pushing the bike. Performance feels way better.

But...
When the bike is idling, or cruising along in low speed, the engine has a somewhat more metallic clattering sound. Is this a danger sound for the engine?