Re: Engines that are prone to sludge

Toyota news

http://yotarepair.com/News_release.html

http://yotarepair.com/Sludge_Zone.html

http://yotarepair.com/My%20Opinion.html



"Bill Putney" <bptn@[EMAIL PROTECTED]
> wrote in message 
news:6f105rF97j17U1@[EMAIL PROTECTED]
> HLS wrote:
>>
>> <johngdole@[EMAIL PROTECTED]
> wrote in message 
>>
news:5987752c-4f1d-4983-866a-23127cf4257e@[EMAIL PROTECTED]
>> The 7500 mile interval is not correct. In 2004 Toyota has lowered that
>> interval down to 5000 for ALL Toyota/Lexus engines while GM and Honda
>> pushed it to 12,000 miles during this period.
>>
>> When I started to buy a Toyota, I asked about that sludging condition. 
>> They indeed
>> recommended a shorter than original change interval, and told me that
in 
>> every case
>> that there had been a problem, the owner had not maintained the 
>> recommended interval.
>
> I don't buy that - I'd take that with a grain of salt.  People make that

> kind of statement often based on very little more than thin air.  There
is 
> no question that some engines are way less tolerant of stretched out 
> maintenance than others.  Other factors come into play, like if the 
> vehicle sees a lot of short-trip and/or stop and go driving vs. mostly 
> highway commutes.  IOW - with certain engines, long oil change intervals

> may not do it in if most of its driving is daily highway commutes, but 
> give it OK change intervals, and do mostly short-trip/stop-and-go, and
it 
> will likely fail.  Combine longer change intervals with short trip and 
> stop and go, and it will surely fail.  Another engine could tolerate
both 
> without a problem.
>
>> BUT, there were also some issues with the PCV system that were
discussed 
>> on this
>> newsgroup that may have also influenced the sludging.  IIRC, they had 
>> reduced the
>> ventilation action and that could well influence oil sludging.
>
> I have a theory that there was technical discussion within the industry 
> where, in the lab and road testing, they were seeing some measurable 
> incremental pollution control advantage in narrowing down crankcase 
> venting and oil drain holes (the sort of thing that papers are published

> on in technical societies), so several companies decided to try it out 
> without really knowing the longer-term effects - IOW, unintended 
> consequences, being prone to sludging being one of the unintended 
> consequences.  IOW - a lesson learned.
>
>> I believe that our 2007 has a longer change interval than 5000 miles,
but 
>> I never let it
>> go so long anyway.
>
> Bill Putney
> (To reply by e-mail, replace the last letter of the alphabet in my
address 
> with the letter 'x')