Synthetic ruin Yamaha engine?

Status
Not open for further replies.
I'm not buying that that conversation ever took place.

There is nothing that the correct dino for an application does better than a correct synthetic. If this story actually happened, then that's more of a problem of the wrong type of syn rather than just the fact that it's syn. Dumb.
 
Mechanic who sells engine overhaul services-"Don't use synthetic oil"

Company that sells new cars-"Change your oil every 10,000 mi. and your transmission fluid, never"

Company that sells motor oil-"Use synthetic oil and change it every 3,000 miles"

I would think that these people are looking out for THEIR bottom lines more than yours.
 
Quote:
I think the mechanic may know lots about motorcycle engines, but very little about lubricants.


True. And the same applies to many mechanical engineers who have not majored in chemisry and/or triboloby.

Quote:
The bearings that revolve around the crank..(babbit)?....can't tolerate synthetic oil. It seems the bike doesn't have the rpms necessary to circulate the synthetic oil around the crank...so, you end up with literally metal on metal..hence the ruined engine....Now, before ya'll pick me to pieces, I'm no mechanic...understood half of what he was saying..but, the engine on the bench was proof. He told me and I quote "synthetic in crotch rockets is fantastic!, but, in low revving bikes....dino only" I guess that's why my buddy uses Harley conventional in his now 50,000 dollar Rocker "C".


I am afraid there is a lot of misunderstanding of basic mechanics and synthetic oil formulatons.
 
Last edited:
If you had read the entire thread from your link, you will see that the original poster "silenthill" replies "IT'S A STORY, I clearly said "FOOD FOR THOUGHT". (A "story", as in once upon a time...)
 
There is so much misinformation and Amsoil peddling on Vulcan Forums that I don't even know where to begin to try to re-educate that crowd. They've been brainwashed for the most part, and if you try to question the marketing [censored] spread by their resident Amsoil sponsor, you will just get yourself banned.

Please do yourself a favor and avoid Vulcan Forums for any sort of oil related subjects. Their model specific forums are good though.
 
I've never heard of a true story about a vehicle using the correct weight oil, be it regular or synthetic that caused the amount of damage, like the guy in the "story" posted. Maybe if you were running 0-20 wt, in a motor that you turned into a drag strip only bike where you hit the red line continually, might be able to cause that amount of damage. I gotta throw the [censored] flag on that one.,,
 
The story has more to do with putting an oil in the motor that was way too viscous and then reving the motor too hard before the oil was warm.

I don't see how the oil was to blame:
A) the oil was too thick,
B) the owner improperly used the motor with improper viscosity oil
 
Originally Posted By: MolaKule
Quote:
I think the mechanic may know lots about motorcycle engines, but very little about lubricants.


True. And the same applies to many mechanical engineers who have not majored in chemisry and/or triboloby.

Quote:
The bearings that revolve around the crank..(babbit)?....can't tolerate synthetic oil. It seems the bike doesn't have the rpms necessary to circulate the synthetic oil around the crank...so, you end up with literally metal on metal..hence the ruined engine....Now, before ya'll pick me to pieces, I'm no mechanic...understood half of what he was saying..but, the engine on the bench was proof. He told me and I quote "synthetic in crotch rockets is fantastic!, but, in low revving bikes....dino only" I guess that's why my buddy uses Harley conventional in his now 50,000 dollar Rocker "C".


I am afraid there is a lot of misunderstanding of basic mechanics and synthetic oil formulatons.

I wonder of a Group III would be OK in this application. I use it in my "slow turning" BMW airhead.
smile.gif
 
Last edited:
Group III is only considered "synthetic" in the USA. I wonder if it only blows up engines made in/operated the USA, since in Europe its considered just severely hydrocracked dino. LOL
 
Last edited:
I'm sure the mechanic has a closet full of edison bulbs so he can avoid the chinese curly lights.
 
I am now told Harley bearings are of a design that the slipperiness of synthetic oil causes them to not spin and develop a flat spot. Other motorcycle bearings are of a different design and don't have this problem. That is what I am told. I have no idea. Does this make sense to anyone?
 
I've been told you cannot use synthetic because of the wet clutch using the same oil.

Here's some text from the following website:

http://www.calsci.com/motorcycleinfo/Oils1.html

"There are a few special problem areas for motorcycle oil. Most motorcycles have wet clutches, which means the motor oil runs through the clutch. If the motor oil has too much molybdenum in it, there are fears that the clutch can start slipping. No one I know has ever actually had this happen to them, but the warnings are all over your owners' manual and the oil companies' web pages. On the back of all certified oil cans is a circular stamp with the certification. Avoid oils that say "energy conserving" in the bottom half of the donut. These oils contain friction modifier additives that could cause clutch slipping over time. Essentially all 0w-20, 5w30 and 10w30 oils are energy conserving, and should not be used in your motorcycle.

Most motorcycles run the engine oil through the transmission, and the transmission gears are very hard on the oil's VII package. This means that over a couple thousand miles, the oil's viscosity can break down. Standard car oils are only good for typically 1500 miles before they've lost about half of their viscosity. Remember, 10w-40 oils contain a lot of VIIs which tend to shear in your transmission, so I believe 10w-40 oils should be avoided. You can't use 10w30 because of the friction modifiers. This doesn't leave much. Commercial 15w40 oils are a good choice, because they have relatively few VIIs which are the more expensive shear-stable sort. Synthetics typically don't contain much of a VII package, so shear is not as big an issue with them."

My dealer has told me several times that I should not use synthetic oil in my Yamaha V-Star because of the wet clutch system. I figure it's no big deal as I only ride about a 1,500 miles per year, and always change the oil at the end of the season.
 
Bearngs that don't "spin"? Well, I suppose the rod bearings "spin" around the crankshaft but they get oil under pressure.
 
Last edited:
This is not about the wet clutch, which can be damaged by friction modifiers, it is about bearings not spinning, supposedly because the oil is too slick. It sounds more like a design flaw.

In a motorcycle you use a motorcycle oil because energy saving oil will damage the clutch disks. Not making them too slick, actually making them sticky. I had to replace the clutch disks on my Rebel because the previous owner did not use the correct oil.
 
Originally Posted By: Boatowner
This is not about the wet clutch, which can be damaged by friction modifiers, it is about bearings not spinning, supposedly because the oil is too slick. It sounds more like a design flaw.

In a motorcycle you use a motorcycle oil because energy saving oil will damage the clutch disks. Not making them too slick, actually making them sticky. I had to replace the clutch disks on my Rebel because the previous owner did not use the correct oil.


I seem to remember reading or hearing something similar. It was on ball and roller bearing crankshafts. The theory was the oil was so slippery the ball or roller would skid and flatspot as opposed to rolling normally. This has not prevented me from using synthetic in my ball /roller bearing cranked bikes. I like living on the edge.
 
Last edited:
Eh, Harley uses roller bearings in the lower end. Once upon a time, they "discouraged" the use of synthetic oils in their bikes, and yes, the fear was that the oil would be too slippery and cause the bearings to "skate" instead of roll.

A few years ago, they started marketing Genuine Harley Synthetic oil, and then it was "OK"

I actually received a letter from Harley, stating that it was OK to use synthetic oil in the crankcase.

They also sent me a letter (as I requested) stating that Mobil 1 or Amsoil synthetic motorcycle-specific oil would not void their warranty.
 
Originally Posted By: JetStar

I seem to remember reading or hearing something similar. It was on ball and roller bearing crankshafts. The theory was the oil was so slippery the ball or roller would skid and flatspot as opposed to rolling normally. This has not prevented me from using synthetic in my ball /roller bearing cranked bikes. I like living on the edge.

I've heard about that - years ago. Never actually come across it, though. It was a bulletin from SKF alerted me to the possibility,but I think it's relatively rare.
I did perk up when I read it, as two of my bike engines are ball-bearing crankshafts and got a little bit concerned for about five seconds.
Otoh - I managed to kill one of those crankshaft bearings. On a cold and frosty morning, started up the bike, gave it the normal couple of minutes warming up, pulled the clutch in, knocked it into 1st gear and there was almightly clank noise. The 20w/50 oil I was using was wrong for that morning and the clutch pack had stuck together just a little bit too much, imposing a shock load on the #4 outboard roller bearing.
Funny how, in well over 200,000 miles of courier work, in all sorts of conditons and who knows how many cold starts there was never a trace of a problem, but I hold my hands up - I had planned to drop the oil and put in a 10w/40 that weekend but didn't get around to it.
My fault for that one. I've still got the engine, and another one with a different gear fault, to make one out of the two.
 
Status
Not open for further replies.

Similar threads

BigJohn
Story of buying a used bike....
2
Replies
24
Views
871
97prizm
V
To blend or not to blend is the question (HPL and Renewable Lubricants)?
Replies
11
Views
613
BusyLittleShop
V
New Honda CRF250F
2 3
Replies
41
Views
4K
irv
V
AMSOIL Metric Motorcycle OR Dirt Bike??
2
Replies
32
Views
3K
Bonz
OVERKILL
Interesting unintended fix - 2002 Yamaha 225 dirt bike
Replies
14
Views
1K
OVERKILL
Back
Top Bottom