Re: Engines that are prone to sludge

On Sat, 26 Jul 2008 12:03:07 -0400, Bill Putney <bptn@[EMAIL PROTECTED]
>
wrote:


>
>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.
>
Haven't kept up with it, but I thought that inadequate oil drain
passages in the heads was determined to be the cause of the "sludge"
problem in some Toyotas.
IOW, overheating of the oil by the heads causing "coking" of the oil.
I never worry about short trips causing oil problems in my cars (none
Toyotas) since I do 3k oil changes.  More concerned about that
prematurely rusting my exhaust.  But hey, I don't worry much anyway.

--Vic