Only use conventional oil after 20k miles?

[Rodsct]

My motorcycle mechanic said that if a Kawi bike has more than 20 000miles on it is not convenient to use synthetic oil because it is too thin for the engine, and I won’t find a suitable thicker one. If I use the synthetic type it will start to burn oil and leaks will start all over.
I have serious doubts about what he said not to say he is full of sh…!
Or is there any basis for such a claim?
Opinions?

[Nightmare]

That guy is a jerk. Syn. oil justy thins faster than conventional. It is not thinner. 10w40 is 10w40 syn or conventional.

[JBearSVT]

Don't you mean slower?

[Beer4Blood]

i believe slower is the answer. seeing as you can run your between 5k-7k miles b4 an oil change on syn oil and only 3k-45k on conv oil, no reason it shouldnt be different on moto oil. syn=best oil my bikes have always run cooler and smoother on syn oil

[LimeBobZX14R]

like he said..that mechanic should be working on bicycles...but then again maybe not

[Crazyninja]

oil claims are so biased. Oil choices are like a religion and can cause great arguments.
My 2005 GTO came with synthetic oil (mobile 1) and that's all i have ever put in as that is what the factory reccomends.

In a few years i may be able to tell you the advantages of synthetic. I can't right now without tearing down an engine that has high mileage that has ran synthetic.

I just purchased kawasaki synthetic 10w40 for my next change.

[Rodsct]

That mechanic is good, for some things, he is very careful with the bike and, paint and finish. But he does have several weird ideas, the last time he told me NOT to remove the gas tank of my bike, not to touch it! I even posted a tread here to ask you guys why.
And then I removed it to service the air filter with no problems at all! What the hell did he say that for? No wonder I do just about everything to my bike now.
He is a cool dude, never the less. Gives his clients free stuff; pen knifes, good Repsol eyeglasses, T shirts etc. etc.
But then again that doesn’t make him a good mechanic.

[JBearSVT]

Wait, now I'm curious. You have to find out why he didn't want you to remove or even touch your fuel tank.

[Rodsct]

Originally Posted by JBearSVT

Wait, now I'm curious. You have to find out why he didn't want you to remove or even touch your fuel tank.

Hi, JBearSVT, I once thought that mechanic might be trying to hide something form me, but everything under the tank is perfectly ok.
My guess is that he may not want me to remove the tank because if I do so, I might start doing more and more to my bike and he will no longer have me as a client. Pretty obvious reason, I think.
The dude seems to be overworked, I’ve found him nearly asleep like a horse standing or half way though a repair sequence, not on my bike.
There are not many bike shops in Fayetteville.

This guy seems like a good candidate for Rocketman’s thread about weird people!

[JBearSVT]

I dunno. Usually when a tech is that emphatic about something, he has some explanation. It may be total BS, but they believe it anyway.

[Rodsct]

Originally Posted by JBearSVT

I dunno. Usually when a tech is that emphatic about something, he has some explanation. It may be total BS, but they believe it anyway.

Yep maybe, but beneath the tank there’s nothing but two wires for the fuel sensor a vacuum valve, a thin vacuum tube to the intake manifold and the fuel line to the carbs.
I see no reason to say NOT to remove the tank. Besides, after I removed it and serviced the air box, the bike runs better than ever.

[JBearSVT]

Indeed, I've had my tank off at least a dozen times with no ill effects... which is why I'm wondering what the potential issue could be.

[185EZ]

Originally Posted by Crazyninja

In a few years i may be able to tell you the advantages of synthetic. I can't right now without tearing down an engine that has high mileage that has ran synthetic..

DAMN, I wanna give you a hug.
Synthetics are great but all their tests in the world can't prove that they work any better than conventional oil for the long haul.
Have they run two identical motors side by side for 30k miles and torn them apart to prove their exceptional performance? no
uh oh, I hear Amsoil calling

[zaneyzrex]

there are more than enough people out there that have switched between dino and synthetic and had lots of leaks show up... sythetic is a smaller molecule so it will find its way thru older gaskets ......
as for being better or not.... do the tests yourself and find out.......

[JKL1960]

Originally Posted by zaneyzrex

there are more than enough people out there that have switched between dino and synthetic and had lots of leaks show up... sythetic is a smaller molecule so it will find its way thru older gaskets ......
as for being better or not.... do the tests yourself and find out.......

I was just discussing this with a guy the other day. We had both heard of high mileage motors leaking oil when switched to synthetic. One of the jobs of oil is to swell seals so I'm skeptical that it leaks out because it is more slippery. I suspect that it is because it cleans better. The old high mileage motor probably has worn seals but they don't leak because the dino oil isn't cleaning out all the accumulated deposits on the seal. When it is switched to synth these deposits get cleaned up and now the weak seals show up. That is just an educated guess.

I'd be hesitant to switch a high mileage motor that has always run dino oil to synth. Although if the motor is fine it shouldn't be a problem. I would keep using synth if it always has.

If an oil is too thin you won't have good pressure. Synthetic does a better job of maintaining viscosity so I don't buy this argument.

[Rodsct]

Originally Posted by JKL1960

I was just discussing this with a guy the other day. We had both heard of high mileage motors leaking oil when switched to synthetic. One of the jobs of oil is to swell seals so I'm skeptical that it leaks out because it is more slippery. I suspect that it is because it cleans better. The old high mileage motor probably has worn seals but they don't leak because the dino oil isn't cleaning out all the accumulated deposits on the seal. When it is switched to synth these deposits get cleaned up and now the weak seals show up. That is just an educated guess.

I'd be hesitant to switch a high mileage motor that has always run dino oil to synth. Although if the motor is fine it shouldn't be a problem. I would keep using synth if it always has.

If an oil is too thin you won't have good pressure. Synthetic does a better job of maintaining viscosity so I don't buy this argument.

Now that you mention this, a couple of years back I had a 1984 Rabbit cabriolet, very nicely kept car, original paint and all, looked brand new! It was plagued with horrible electrical problems that finally caused it to meet its demise with me. (I sold the thing)
I filled the engine with synthetic oil and all of a sudden oil leaks, real nasty ones too, started all over the engine. I had to throw away 90$ worth of synth, just to fill it up again with mineral oil. The leaks where reduced but didn’t go away all together.
Now I’m VERY reluctant to use synth oil in my 1990 bike. It has absolutely no leaks and I’d like to keep it that way. Maybe I’m wrong and nothing would happen if I use it, and it could be better for my bike, but then again we would start all over again with the discussion we had in a similar thread.
Round and round we go.

[JBearSVT]

Originally Posted by JKL1960

I was just discussing this with a guy the other day. We had both heard of high mileage motors leaking oil when switched to synthetic. One of the jobs of oil is to swell seals so I'm skeptical that it leaks out because it is more slippery. I suspect that it is because it cleans better. The old high mileage motor probably has worn seals but they don't leak because the dino oil isn't cleaning out all the accumulated deposits on the seal. When it is switched to synth these deposits get cleaned up and now the weak seals show up. That is just an educated guess.

I'd be hesitant to switch a high mileage motor that has always run dino oil to synth. Although if the motor is fine it shouldn't be a problem. I would keep using synth if it always has.

If an oil is too thin you won't have good pressure. Synthetic does a better job of maintaining viscosity so I don't buy this argument.

This is exactly true. Dino oil is full of contaminants right out of the bottle that true synthetic isn't. Synthetic is also capable of absorbing exponentially more crap produced during the combustion process, which is one of the reasons it stays effective for longer change intervals. If you have run an engine with dino oil for a long enough time, you can expect there to be some related garbage in there which is compromising the integrity of the seals. While it may not be leaking, it is in fact only a false seal. If you run synthetic at this point the odds are very good that you're going to spring leaks, because it will clear them out. It's worth mentioning that unless the seals were severely compromised, they will stop leaking eventually as the synthetic fills them in. I know of one manufacturer that actually sells a conversion treatment, which speeds up the process of flushing out the crap and preparing a higher mileage conventionally lubed engine for a synthetic future.

Concurrently, an engine which has always used synthetic will generally stay tight as a drum with it (that's you, Rod), long after it would have started leaking with conventional. If you keep using synth and it starts leaking, rest assured that it isn't the oil's fault and it would have anyway because something else is wrong. This isn't just what I observed in my decades with the auto repair industry, it's *science.

*science which doesn't support the argument that the molecules are smaller, they are simply more uniform- which actually makes it less likely to leak... but that's a whole other topic

[Rodsct]

Originally Posted by JBearSVT

This is exactly true. Dino oil is full of contaminants right out of the bottle that true synthetic isn't. Synthetic is also capable of absorbing exponentially more crap produced during the combustion process, which is one of the reasons it stays effective for longer change intervals. If you have run an engine with dino oil for a long enough time, you can expect there to be some related garbage in there which is compromising the integrity of the seals. While it may not be leaking, it is in fact only a false seal. If you run synthetic at this point the odds are very good that you're going to spring leaks, because it will clear them out. It's worth mentioning that unless the seals were severely compromised, they will stop leaking eventually as the synthetic fills them in. I know of one manufacturer that actually sells a conversion treatment, which speeds up the process of flushing out the crap and preparing a higher mileage conventionally lubed engine for a synthetic future.

Concurrently, an engine which has always used synthetic will generally stay tight as a drum with it (that's you, Rod), long after it would have started leaking with conventional. If you keep using synth and it starts leaking, rest assured that it isn't the oil's fault and it would have anyway because something else is wrong. This isn't just what I observed in my decades with the auto repair industry, it's *science.

*science which doesn't support the argument that the molecules are smaller, they are simply more uniform- which actually makes it less likely to leak... but that's a whole other topic

So I guess that I’ve my old bike it tight with synth then the very best thing is to continue to run with synth ! I don’t know what it had when I bought the bike, but thanks to my mechanic’s “no synth after 20k miles” ideas, he filled it up with “Maxims semi -synth” the last time.
Now I suppose it would be safe to fill it with full synth because after a year my bike has proven to me that it’s more than worth keeping

[JBearSVT]

OH... I should have phrased "that's you Rod" as a question. For some reason I was assuming it had always had full synthetic, and he wanted to stop because the mileage was getting up there. Now I'm reading it again and that doesn't necessarily look like the case?

[Rodsct]

Originally Posted by JBearSVT

OH... I should have phrased "that's you Rod" as a question. For some reason I was assuming it had always had full synthetic, and he wanted to stop because the mileage was getting up there. Now I'm reading it again and that doesn't necessarily look like the case?

Why?

We’ve been going over and over with this Dino vs. Synth oil topic for weeks and I’m still at a loss. I’m more confused than ever!

I’m sorry, I should have said before that I’ve only had my current bike for about a year now. A year that I spent most of the time fixing it and not riding it.
It has absolutely no leaks, the engine is dry! Except… maybe around the area of the oil filter but that may be normal anyway.
It ran on semi – synth with no problems for a year, but very very few miles!
All it needs is an oil change and it will be done! Ready for riding!
Regards!