Why synthetic oil weeps

Interestingly, it's not a Japanese bike. The KZP's were made in Lincoln
Nebraska until last May. So it's actually American. Harley guys still hate
it though

I'd think too that things would usually be upgraded except for one point.
This is a cop bike.. not a consumer bike. The cop fleets want to deal with
as few parts differences as possible, so I can see a case for thinking they
didn't change the seals. In fact, the only real observable mechanical
difference on these was that in '03, they went from a 1-piston to a
2-piston front brake caliper. From 83 until the last one in 05, they are
virtually identical. Hey.. I actually did a page on that:

http://users.crocker.com/~mwilliams/KZP.htm

Sir... I think you think too much

<leaning in and whispering> Hey... Oswald was the only gunman.

Mike

 

David... YOU ROCK. Thanks! This is one of the highest quality answers I've
seen on usenet in years. A question or two will follow below.

I still can't believe how good this data is. To fill in the corners of my
understanding on this...

1. Do you think a 1982 design where there was no commercial pressure (it's
a police bike where parts changes aren't real welcome) might be old enough
to still have the old technology seals in a 99 copy of the engine?

2. Can operating at a temp higher than typical (but I do think still in the
range for what this was designed to do) for extended periods
cause/exacerbate the seeping?

3. I'm going to rebuild the whole thing this winter. I'm not much up on
seals but are there any steps I could take to avoid a repeat? Go non-oem?
Look for certain properties?

Thanks again.

Mike

 

Are you 100% sure of this? I am not sure but the seals and
O-rings in all the bikes I've run full synthetic oil in somehow
looks very "standard", Nitrile in other words. The seals I have
bought as replacement at non-motorcycle shops have been
Nitrile, I'm sure about that, and have given me no problems.

I have never seen any advice anywhere else about using
silicone rubber for sealing synthetic engine oil. Actually, I
don't even know if radial shaft seals are available in silicone.

 

Oil seals are very generic. I doubt Kawasaki buys seals so much by exact
spec from original design as by size. For example there are a lot of
Kawasaki engines which use the same valve stem seal as the original Z in
1972 or 1973.

Bearings are much the same. Sizes are usually standard so when you go to
rebuild talk to local bearing vendors. Often one can get top quality
Timken or similar bearings for the same to much less than whatever comes
over the Kawasaki parts counter. Especially Kawasaki who has the
reputation for the highest parts prices. I bought a Keihin CV-40
throttle slide from the Harley-Davidson dealer, in stock, for $38 while
the Kawasaki dealer offered to order one for me for $115. No, it wasn't
exactly the same part but all I needed was the rubber diaphragm.

What I've read of the oil vs oil seal issue suggests it is the oil which
was adjusted to make the change, after all the oil had to be
"compatible" to be marketable. The mechanism which kept an oil seal
working as long as it did wasn't widely understood. The designers of
ancient synthetic oil didn't know of it so they didn't design for it.
They now know.

What might not have been so clear in my prior posting is if an oil
swells a seal then a tighter fit is made, and the seal wears faster. If
a different oil does not swell the seal as much then the seal fits
looser and leaks. If one always uses the same oil then there isn't a
problem.

 

I use synthetic by preference (cars and bikes), and the only point I will
yield to leakage is that if an engine loses enough between oil changes, I
will use the cheaper natural oil. If I don't have to add much if any between
changes, then synthetic is all I'll use. (Especially in an air cooled bike,
I prefer synthetic's better heat tolerance, aside from flowing better when
cold to minimize cold/dry starting.)

 

I heard Elvis was back-up.....

 

It was very common for normally non leaking automobiles to spring leaks
after switching to synthetic oil. I fail to see why motorcycles should be
any different.

Ed Cregger

 

Sez you.

It's a problem I've never heard of before, and I've got a number of old
bikes I run on synth.

I repeat - I think this entire thread is a red herring and a waste of
bandwidth.

 

Quaker State says no.

"Synthetic oils do not cause engine oil leaks. Deteriorated and
hardened seals and gasket material cause engine oil leaks."

http://www.quakerstate.com/pages/carcare/whattoknow.asp

I've heard it suggested that synthetics may sometimes loosen up the
accumulated crud that's preventing a leak, but even if true, that would
suggest that you're well on the way to leaks already.

 

Well, until I got into this thread, I'd never heard of you but that is
inconclusive evidence of your nonexistence.

Elvis

 

Your well-articulated insight is much appreciated David. If any of the
sources you cite are available as links, I'd be very interested in learning
more.

Mike

 

It used to be a very common topic of discussion in the hot rod mags back
when the synthetics first came out.

Cars and trucks that had no history of oil leaks would mysteriously begin
dripping oil from various locations after switching to synthetic oil. I saw
it myself. Some of the vehicles I had serviced for a year or two with
petroleum based lubricants and they did not have a problem leaking. Once the
synthetic was installed, the leaks began.

The dealerships used to claim that there was a lower viscosity component in
the synthetic mix and increased detergents. Me, I'm not a chemist, so I
don't really know. But I do know that the phenomenon was real - not
imagined.

Ed Cregger

 

See my response to Older Gentleman. I was there, I saw it happen with no
other explanation offered by the auto manufacturers. The dealerships were
aware of the problem and used to curse whenever a leaking engine lubed with
synthetic rolled into their garage.

Yes, I agree that an engine with old, dried out gaskets would be more prone
to leakage if the oil was switched from petroleum based lubricants to
synthetic based lubricants. But I've also seen new vehicles experience the
same problem.

Ed Cregger

 

So a synthetic 10 weight oil was lower viscosity than a mineral 10
weight?

Yeah, right.

 

I'd be more inclined to buy into this if I saw a manufacturer (oil or
vehicle) recommend against synthetics. If a mfr figured synthetic was
causing warranty problems, I think they'd most likely have something
official published recommending against it.

About the only recommendation I've ever heard is to run rings in
on dino before switching to synthetic. I've been running Mobil 1 for
quite a while now on a block with 50-60K on it with no problems.

I also wouldn't take everything I heard at a dealership as gospel.
Some dealers can be really good, some not so good. A bulletin
or owners manual would be a lot more convincing.

Personally, I figure synthetic oil weeps because it's so badly
misunderstood.

 

Honor is due... honor is due.


--
"Well," Brahma said, "even after ten thousand explanations, a fool is no
wiser, but an intelligent man requires only two thousand five hundred."
- The Mahabharata

Don't send me email replies -- this is a honeypot address for unsolicited
commercial email.

 

(The Older Gentleman) wrote in

I can't say if the viscosity was actually lower when i changed the 90W gear
lube in my transmission but it seemed about the same. It could be that in
Ed's case the oil may be quaranteed 10w40 but measurement shows that it is
closer to 3w40. Something was going on and we are guessing.

pierce

 

I really can't see a ube manufacturer, SAE and all that, declaring lube
to be 10w when it's really 3w.

An 10w dino[1] oil is the same viscosity as 10w synthetic, or 10w
vegetable, for that matter.

Now, using a lower viscosity oil than recommended - say 5 or even 10
instead of 20 or 50: that I can understand as a leak provoker.

[1] A US expression I rather like.

 

Yes, I've heard this too.

I ran my Ducati on fully synth from the start (as recommended). It took
15-20,000 miles before the engine was nicely loose!

 

The detergent quality of the synthetic cleans out any varnish or gum
built up from using dino oil.

Thanks,Ripper
We Need DEATH SQUADS in the USA to Get Rid of Terrorists AND Street
Gangs!
BOYCOTT CLASSMATES.COM for their PHONY FREE TRIAL MEMBERSHIP (NOT)