Why synthetic oil weeps

I've heard in numerous corners that when you run synthetic oil in an engine
that spent it's early life living on standard oil that it weeps. There's a
commercial for some brand of oil on tv now that explicitly states that the
synthetic weepage rumor is pure urban myth. Yet my KZ1000P which has been
treated rather well over it's mere 28k mi is progressively weeping more
with each ride. It's significant at more than 1ml/mi now. Virtually no oil
out the exhaust other than the valve guide seal stuff at start up. I'm
giving this phenomena more credence than the oil company would like but I'm
hopefully still open minded. Any day now I'll be taking the KZp out of
service and starting the process of rebuilding the engine.

My question is... does anyone KNOW from some kind of science that was done
on this problem whether this is a real issue, and then if so, did that
science get to the bottom of what the cause was? I've heard a "molecular
size" idea advanced but he was making it up as he went along. I'm looking
for informed input on this... I've heard all the speculation about this
anyone needs for a couple of lifetimes now Thanks in advance for any help
you can give me on this.

Mike

 

<snip>

It's bollocks. Your Kawa has developed an oil leak. Shit happens.

 

I've never, ever experienced an oil leak that I could put down to the
use of synthetic oil.

 

If the oil is disappearing when you ride (you said 1ml/mi) and
not when parked (or does it indeed form an oil slick?), it's
not what I'd call weeping but burning or spitting out oil.

A 1000cc bike that needs an engine rebuild at 28k miles !!??
Someone has used the bike to it's full potential or mistreated
it, no wonder it uses oil.

And, to add my voice to the choir: I can't really say I've
seen a difference with synthetic when it comes to leakage.

 

I have had experience with pure synthetic and it leaks more than with
semi-synthetic. Whether that is due to the oil or just my perception I
don't know.

pierce

 

It think this is mostly BS with newer engines made in the last 15 years.
Now, for the old stuff, yes you will have a problem running synth in older
engines with plane old rubber seals. The synth oil will degrade older style
rubber seals and thus leak. Therefore you need to upgrade your seals to
silicone based materials.

In your case, the fact that the motor has 28k on orignial seals might be a
major contributor.

 

Thanks but I'm really looking for data that goes a little deeper than this.
I invented the in your face all-style and no-substance reply I need more
this time. BTW.. seeping from at least a dozen places, all of which
occurred over 6000 miles.

Mike

 

Good stuff now... this is anecdotal and doesn't prove the point but it
still contributes. Thanks.

Mike

 

I have a known issue with the valve guide oil seals. AND I have significant
surface oil appearing on the engine from numerous places on the top end.

I have done a great deal of drilling with it at slow speed but always
breeze it out appropriately.

http://users.crocker.com/~mwilliams/Parking_Lot_Moves.htm if you're
interested.

I've also been around a LOT of KZP trainers that use conventional oil and
no seepage like I see on this one.

Thanks. The design on this goes back to the 80's (really 70's) and I'm not
sure they ever upgraded the seal technology along the way.

Mike

 

Thanks Pierce. What is the extent of the problem you've noticed? How long
before change over did it take to manifest?

Mike

 

THIS is a FANTASTIC clue... thanks. It's a 99 but it's a design that goes
back to 82. No idea if the seal technology was ever upgraded. I know police
departments would never spring for synthetic.. they let them suffer
detonation in fact by running the lower octane fuel.

Thanks.

Mike

 

On the transmission in question it seemed to leak worse immediately after
the change. I changed it back and it still leaked but it wasn't as bad.
If 0 is dry and 10 is pouring out the dino oil leaked about a 4. With
synthetic it leaked about a 6. After changing it back it leaked about a 5.

pierce

 

Can I ask you a question Mike. Have you ever posted to this NG under a
different name?

 

It's an old bike.

As has been pointed out, seals dry out.

 

I think it is safe yo say that the Japanese will not still be using
1982-era seals, ffs.

Am I the only person who thinks this entire thread is a red herring?

 

There is nothing about "synthetic" which equates to "more detergent
action." Motor oil has exactly the detergent properties its designers
intended, whether it be manufactured with synthetic or refined processes.

Synthetic motor oil has exactly the same chemistry as refined oil. The
difference is that use of synthetic processes allow the designer to
carefully pick and choose his hydrocarbon cocktail while refining more
closely resembles successive filtering to get the final product. This is
why a Court of Arbitration decided in Castrol's favor in Mobil vs.
Castrol over the definition of "synthetic" when applied to motor oil.
Castrol used additional refining steps and successfully claimed the end
result was indistinguishable from "pure synthetic."

Back to "pure synthetic": its exactly no more and no less than what its
designers do intentionally. Back in ancient days oil designers didn't
know how oil reacted with oil seals. Oil seal makers only knew by trial
and error with refined oils that their product worked. Everybody "knew"
the adage, "always use the same oil for the life of the engine" without
really knowing why. If one changed to a different make or model oil,
often the seals would leak as punishment.

What was learned was that refined oil had stuff which caused oil seals
to swell. That different makes/models of oil swelled seals differently.
That changing to a different oil could cause the old swelling to leach
out resulting in a loose seal. It just so happened this *always*
happened with synthetic oils, creating a reputation which lives in lore
for the past 30 or 40 years.

All oil and oil seal designers know of this situation and address it.
Changing from one brand to another could still aggravate the situation
but no more between brands than crossing between refined and synthetic.

As for detergent action, the so-called Diesel oils, Delo, Delvac,
Rotella-T, will have more than most anything else whether refined or
synthetic.

 

Thank you.. it sounds like an aging mechanism that isn't a surprise. Just
new to me.

Mike

 

Thank you. I'll probably give them a try. This gives me an idea too about
checking outside of my imagination. Maybe there are some good automotive
engine sites as well too.

So you guys have me thinking about this in other directions now. The reason
I switched over to synthetic wasn't so much for traditional longevity
reasons as it was for heat management. I'm doing drills at very low speeds
and it's air-cooled.. in looking into synth, I found I could get a 10-20
degree drop in engine temp and that was good enough reason for me.
Experimentation of many kinds of synthetic and synth-blend oils revealed
basically one oil that gave me a KILLER clutch feel... Mobil1 15W50. The
other stuff ranged between a vague feel and grabby as hell as temp rose.

So what I'm thinking now is that while the first 13k mi of this bike's life
were regular cop work under a lady cop (sorry.. I just assume she didn't
beat on it as much as a guy), it got progressively more operating hours at
low speed living in the friction zone (I operate under the assumption I'll
put a new clutch in each year). More time at temperature. I wonder if heat
takes out seals? I don't think I'm OVERheating it because I am
conscientious about breezing it out regularly, but it runs warmer than
most.

Mike

 

Thanks Pierce... sounds like this isn't what happened on mine. It was fine
for a while. The leak happened after 2-3 oil changes. Tilts things a little
bit in the direction of "the heat theory" above In the back of my mind,
that valve guide oil seal problem I mentioned before might have exacerbated
it. The VGOS's led to carbon fouling in the combustion chamber and I'm sure
that was behind a detonation issue I struggled with for some time. I did
"the water trick" and I'm running octane booster until I get the heads off
this winter.. det is fully under control.

Mike

 

Sure LJ.. I *think* I posted a question in here some time ago. 1-2 years
ago.. when I was researching the "water trick" in removing carbon fouling
from a combustion chamber. Maybe not but I think so. I am 99.9% certain I
would have posted that under this name. I've only been in a handful of
usenet groups in my "career" and most of my time was spent in just one, all
under this name.

Mike