Question about engine oil sludge

You have probably heard about oil sludge problems causing engine failure on
several engines including the Chrysler 2.7L V6 used in Intrepids from
1998-2004, Toyota 3L V6 used in Camry's and even the Volkswagen 1.8L Turbo
engine used in lots of VWs and Audis. The common reason given is too
infrequent oil changes. The fix is to use synthetic oil and keep it current.

That's what I thought, but last Saturday, I was listening to a show on the
radio in Denver called NAPA auto care. The mechanics said that the sludging
problem is actually caused by a combination of distributor-less high energy
ignition systems and coolant that had not been changed. Evidently, the
fast-rising current spike travelling through the block induces sludging???

I found that very confusing. Do any of you know more, or were these guys
just trying to scare up some business?

Bill D wrote:
> You have probably heard about oil sludge problems causing engine failure on
> several engines including the Chrysler 2.7L V6 used in Intrepids from
> 1998-2004, Toyota 3L V6 used in Camry's and even the Volkswagen 1.8L Turbo
> engine used in lots of VWs and Audis. The common reason given is too
> infrequent oil changes. The fix is to use synthetic oil and keep it current.
>
> That's what I thought, but last Saturday, I was listening to a show on the
> radio in Denver called NAPA auto care. The mechanics said that the sludging
> problem is actually caused by a combination of distributor-less high energy
> ignition systems and coolant that had not been changed. Evidently, the
> fast-rising current spike travelling through the block induces sludging???
>
> I found that very confusing. Do any of you know more, or were these guys
> just trying to scare up some business?

I've certainly heard lots about the problem, but that's the first I've
heard that explanation. I'm not ready to totally discount it until I
hear more, but I'm having a very hard time imagining how coolant (that
is not leaking internally) can cause sludge in the crankcase! Are the
ignition current spikes supposed to disturb gasket interfaces and thus
cause the coolant to leak into the crankcase and form sludge with the oil?

Willing to listen...

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


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Bill D wrote:
> You have probably heard about oil sludge problems causing engine failure on
> several engines including the Chrysler 2.7L V6 used in Intrepids from
> 1998-2004, Toyota 3L V6 used in Camry's and even the Volkswagen 1.8L Turbo
> engine used in lots of VWs and Audis. The common reason given is too
> infrequent oil changes. The fix is to use synthetic oil and keep it current.
>
> That's what I thought, but last Saturday, I was listening to a show on the
> radio in Denver called NAPA auto care. The mechanics said that the sludging
> problem is actually caused by a combination of distributor-less high energy
> ignition systems and coolant that had not been changed. Evidently, the
> fast-rising current spike travelling through the block induces sludging???
>
> I found that very confusing. Do any of you know more, or were these guys
> just trying to scare up some business?

I've certainly heard lots about the problem, but that's the first I've
heard that explanation. I'm not ready to totally discount it until I
hear more, but I'm having a very hard time imagining how coolant (that
is not leaking internally) can cause sludge in the crankcase! Are the
ignition current spikes supposed to disturb gasket interfaces and thus
cause the coolant to leak into the crankcase and form sludge with the oil?

Willing to listen...

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


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> I've certainly heard lots about the problem, but that's the first I've
> heard that explanation. I'm not ready to totally discount it until I hear
> more, but I'm having a very hard time imagining how coolant (that is not
> leaking internally) can cause sludge in the crankcase! Are the ignition
> current spikes supposed to disturb gasket interfaces and thus cause the
> coolant to leak into the crankcase and form sludge with the oil?
>
> Willing to listen...
>

Could it be perhaps that the worn-out coolant becomes less inductive than
the aluminum head? If so, the current would flow into the least inductive
path (remember, this is an AC spike)

Could that potentially cause local heating of small oil passages in the
engine? I think these engines run hotter to meet emissions, and maybe this
is enough to cause sludge?

Inquiring mind need to know!!

> I've certainly heard lots about the problem, but that's the first I've
> heard that explanation. I'm not ready to totally discount it until I hear
> more, but I'm having a very hard time imagining how coolant (that is not
> leaking internally) can cause sludge in the crankcase! Are the ignition
> current spikes supposed to disturb gasket interfaces and thus cause the
> coolant to leak into the crankcase and form sludge with the oil?
>
> Willing to listen...
>

Could it be perhaps that the worn-out coolant becomes less inductive than
the aluminum head? If so, the current would flow into the least inductive
path (remember, this is an AC spike)

Could that potentially cause local heating of small oil passages in the
engine? I think these engines run hotter to meet emissions, and maybe this
is enough to cause sludge?

Inquiring mind need to know!!

Bill Putney wrote:
> Bill D wrote:
>
>
> I've certainly heard lots about the problem, but that's the first I've
> heard that explanation. I'm not ready to totally discount it until I
> hear more, but I'm having a very hard time imagining how coolant (that
> is not leaking internally) can cause sludge in the crankcase! Are the
> ignition current spikes supposed to disturb gasket interfaces and thus
> cause the coolant to leak into the crankcase and form sludge with the oil?
>

Just to give more data: I have not even once changed the coolant in my
2.7l which now has 205,000 kms (127,000 mi). Also I'm on my second
synthetic oil change without catastrophe. And of note: my commute has
recently been reduced from 70kms each way to about 20 kms each way. I
will update the group with any change in the, what I would now call
dependability, of my motor.

Bill Putney wrote:
> Bill D wrote:
>
>
> I've certainly heard lots about the problem, but that's the first I've
> heard that explanation. I'm not ready to totally discount it until I
> hear more, but I'm having a very hard time imagining how coolant (that
> is not leaking internally) can cause sludge in the crankcase! Are the
> ignition current spikes supposed to disturb gasket interfaces and thus
> cause the coolant to leak into the crankcase and form sludge with the oil?
>

Just to give more data: I have not even once changed the coolant in my
2.7l which now has 205,000 kms (127,000 mi). Also I'm on my second
synthetic oil change without catastrophe. And of note: my commute has
recently been reduced from 70kms each way to about 20 kms each way. I
will update the group with any change in the, what I would now call
dependability, of my motor.

pawn wrote:

> Bill Putney wrote:
>
>> Bill D wrote:
>>
>>
>> I've certainly heard lots about the problem, but that's the first I've
>> heard that explanation. I'm not ready to totally discount it until I
>> hear more, but I'm having a very hard time imagining how coolant (that
>> is not leaking internally) can cause sludge in the crankcase! Are the
>> ignition current spikes supposed to disturb gasket interfaces and thus
>> cause the coolant to leak into the crankcase and form sludge with the
>> oil?
>>
>
> Just to give more data: I have not even once changed the coolant in my
> 2.7l which now has 205,000 kms (127,000 mi). Also I'm on my second
> synthetic oil change without catastrophe. And of note: my commute has
> recently been reduced from 70kms each way to about 20 kms each way. I
> will update the group with any change in the, what I would now call
> dependability, of my motor.

I've got exactly the same miles on my '99 2.7L, and it runs fantasticly.
I am changing the coolant for the first time this weekend (don't know
if it was done previously - I bought it with 58k miles on the ticker).
Hope things continue well for you with the synth at this high mileage on
a sludge-prone engine (I assume your point was that you changed over to
synth at high mileage). If no problems so far, you're probably OK, but
IMO you took a big risk. My daily commute is 80 miles, 90+% 55-60 mph.

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


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pawn wrote:

> Bill Putney wrote:
>
>> Bill D wrote:
>>
>>
>> I've certainly heard lots about the problem, but that's the first I've
>> heard that explanation. I'm not ready to totally discount it until I
>> hear more, but I'm having a very hard time imagining how coolant (that
>> is not leaking internally) can cause sludge in the crankcase! Are the
>> ignition current spikes supposed to disturb gasket interfaces and thus
>> cause the coolant to leak into the crankcase and form sludge with the
>> oil?
>>
>
> Just to give more data: I have not even once changed the coolant in my
> 2.7l which now has 205,000 kms (127,000 mi). Also I'm on my second
> synthetic oil change without catastrophe. And of note: my commute has
> recently been reduced from 70kms each way to about 20 kms each way. I
> will update the group with any change in the, what I would now call
> dependability, of my motor.

I've got exactly the same miles on my '99 2.7L, and it runs fantasticly.
I am changing the coolant for the first time this weekend (don't know
if it was done previously - I bought it with 58k miles on the ticker).
Hope things continue well for you with the synth at this high mileage on
a sludge-prone engine (I assume your point was that you changed over to
synth at high mileage). If no problems so far, you're probably OK, but
IMO you took a big risk. My daily commute is 80 miles, 90+% 55-60 mph.

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


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We traditionally call "sludge" is a substance caused by motor oil exposed to
normal motor temperatures plus water and other combustion contamination that
forms a mixture of various compounds that participate out of the oil. Over
time these compounds can coke-up and form a solid mass.

Synthetic oil tends to avoid this by doing a better job of keeping the
compounds in suspension and a better job of dealing with the acids that form
when the compounds are exposed to water. Any detergent oil will quickly
disolve the hardest deposits if change frequently enough, perhaps every 500
miles, till the sludge and hard mass is desolved.

More likely a problem caused by 1. poor design of the lub system, 2. changed
fuel mixtures, 3. failure to use an oil that can deal with the changed fuel
mixtures, and 4. not letting the motor come up to full running temperature.

The reports you hear about spark, coolant, etc., are pure magic.

Richard.