5-20 oil

Another urban legend that refuses to die...

Matt

 

Not an urban legend. The synthetic oil, over a short period of time,
disolves a lot of what the Dyno oil left behind. If that is all that
held the oil in, it WILL leak. And on a Mitsu 3.0, there are LOTS of
places to leak oil around thevalve gear in particular - but oil pan
gaskets and front seals as well.

 

So you're saying that there are no technical reasons to use a blend?
That the only reason is to incrementally cut the cost of the oil and on
the process knowingly dilute some fo the benefits of the synthetic oil?

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')

 

I've heard that "dissolves everything" legend as well. I've never seen
any real data to back this up, and I've put synthetic in a couple of
engines with more than 50K on them with no problems. I think both are
urban legends. People make a change and something happens (a leak) and
human nature is to imply cause and effect to what is likely just a
simple correlation.


Matt

 

I see too many posts on any given week on the LH car forums where
someone has just switched over to synth and now suddenly has serious
problems. One or two a year might be coincidence. 2 a week is not
coincidence.

I also personally experienced it on a high mileage Subaru that I
switched over to synth suddenly. The synth definitely loosened up crap
that got into the lifters. The timing of the onset and what I had to do
to resolve it proved it (to me) in that one case.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')

 

You are a condescending jackass. Stop being such a jerk to everyone in
this forum and go start your own, of you don't like what's being said
here. OK?

 

And yet you obviously continue to read my posts. You must like 'em more
than you let on.

I've been here for well over a decade, and I don't guess I'm going away
anytime soon. You're welcome to cease reading my posts, unless there's
somebody you haven't mentioned who's forcing you to read them.

 

x-no-archive: yes

Only a "condescending jackass" would presume to instruct others to go
start a "forum." I've learned a lot from Stern's posts, and I suspect
others have too. If *YOU* don't like what's being said here, why don't
*YOU* take your own advice and start a "forum."


ps. you top posted.

 

Urban legend. "Sludge and varnish" never keep the oil in.

 

I was really saying that the piston scuffing claim is bogus. Blends are
fine, if cost is a driving factor. And to be honest there are blends
(and straight non-synthetics) out there now that turn in oil-analysis
numbers that are very competitive with pure synthetics. But given that I
like to keep cars 10-20 years (or more), I believe that picking a name
synthetic and sticking with it gives better long-term assurance of a
good oil without constantly hanging around the internet to see how
various formulas have changed this week versus last month.

 

And you are a mechanic??

 

No I'm not. But I am an engineer.

Why do you presume to think that "sludge and varnish," which form at
random and have no structural strength of any significant sort, can
actually form a working seal?

 

I don't know, Steve. I *vividly* remember the one and only time I used
a sudden-flush (kerosene commercial-type flush - came in a quart can) on
a high mileage engine. It was a 1980 Chebby Citation V-6 - the rear
crank seal was the rope-type (not rubber). Before the flush, there were
no leaks. Immediately after the flush - and I mean 5 minutes after the
flush when fresh oil was put in - I laid under the engine with it
running and watched oil streaming out of the rear seal. I have to
believe that the interstices of the rope were sealed up with residue,
and that residue was dissloved away by the flush. A rubber seal isn't
going to have the interstices, but there is that interface between the
seal and the shaft. Now - there's no way an intact soft, non-swolled or
shrunken rubber seal is going to leak, but I could see a special case
where a seal was hard and barely sealing, and a little residue could
make the difference between slight seepage, and steady drip or stream
leakage.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

 

Figures.
Get your hands dirty before you start talking about things you know
nothing about.

No presumption at all on my part.
35 years of experience as a mechanic.
Have you ever attempted to remove a few years accumulation of sludge
and varnish from an engine? It can block up oil galleries so tight
that 60PSI of oil pressure cannot force any oil through. And it takes
a whole lot more than a toothbrush to remove it. Try a chisel.

 

OK, I'll admit that I can see how a rope-type seal *might* work that
way. But even in that case, my hunch is that the "quick flush" spoo
probably attacked the seal directly, not any embedded gunk in it.

 

I don't know you, so I won't brag that I've been inside 5 times as many
engines as you have. So why do you ASSume you've been inside more
engines than I have? Or that I never "get my hands dirty." I'm not a
mechanic, but I've been a car hobbyist for over 20 years.

Have you ever actually removed that kind of baked-and-burned in place
material (I'd hardly call it 'sludge' or 'varnish' at that point) from a
SEAL? I haven't. Yeah, I've chipped it off the bottom of intake
manifolds where the exhaust crossover shield had dropped off, picked it
out of valve springs that have been overheated until they're blue and
limp, and chiseled it off of heads that were warped from overheating or
had been starved for rocker and valve oiling by clogged pusrhods
(Ford)... but I don't think I've ever removed anything from a SEAL that
you couldn't wipe off with a Q-tip and kerosene.

Bill made a good point about rope-type seals being a different animal,
and so are old-style cork/neoprene matrix gaskets. I'll readily admit
those might theoretically be aided by gunk plugging the pores. But a),
I've switched engines with rope seals and cork/neoprene matrix gaskets
to synthetic without them gushing or even leaking, and b) those are
hardly common items in any engine anybody's going to be dealing with on
a regular basis today. I'm more likely to see them working on an old
flathead 6 or 60s v8 than people with an engine that might call for 5W20
oil.

 

Because this is the very stuff of usenet:-

- assumptions
- making bold (and bald) statements grounded in the shifting sands of
supposition and vague recollection
- being all-knowing
- rudeness (incl swearing and offensiveness).

But one can still get decent info and have civilised discussions.

DAS

For direct contact replace nospam with schmetterling
---

[...]

[...]

 

Couldn't have been that the flushing brew ruined a seal or two... No,
that could never happen...


Matt

 

You mean talking about things like you do?

Lots of presumption on your part!

That hardly makes you an expert on oil seal design and function.

A seal and a plug are two different things entirely. You can stuff a
brand new crank seal into and oil passage and likely block it
completely. Likewise, an oil drain plug doesn't make a very good
crankshaft seal, yet it plugs the hole in the oil pan very effectively.
Two totally different concepts. I'll grant you that sludge can make
an effective plug, but it doesn't make an effective seal against a
rotating component.


Matt

 

Nor would it ever happen that residue/"gunk" embedded in the seal was
dissolved away? I could easily picture semi-liquid/semi flexible
residue, over time, slightly displacing the seal where it met the
crankshaft, and then when dissolved/washed away by the flush, there is a
nice new gap between seal and shaft that previously was filled with the
residue without doing much at all to the seal itself.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')