Re: Synthetic Oil

[Cosmo <simond@london.informix.com>]

Kirbert wrote [ edited ]:
>
> 
> You know that varnish that builds up inside an engine over time?  Especially
> under the valve covers?  Well, initial impression is that not only does
> synthetic oil not create this varnish, but it CLEANS it as well! 
 
> In fact, it may have caused the leak -- and this may be why synthetic oil
> gets a reputation for leaking out of cars.  Some of those potential leaks may
> be plugged by the varnish.  When the varnish goes away, the leaks flow.

Interesting theory.  I tried the new Mobil 1 0w-40 oil recently in my SIII
XJ6 and also got leaky rocker gaskets.  Haven't needed to remove them so I
don't know if they are clean inside.  A number of other minor drips appeared
on the floor but I had to cut short my experimentation due to the terrible
oil consumption.  I was burning oil like James Bond's Aston Martin.  Quite
embarassing.  Seemed to lessen greatly after 800 miles but by now that oh
so wonderful oil had turned to the kind of sludge you see at 5,000 miles.

I guess the lighter components of the oil just found it's way through the
more worn parts of the engine and away to freedom.  The car has 111,000 miles
but the PO says the engine was a recon unit at 50,000.

I rang Mobil and spoke to their technical department and a "specialist" told
me that (contrary to all their advertising) an engine over 100,000 miles will
get no benefit from synthetic oil.  I've written a letter of complaint to them
and I'll keep you informed.

 
> BTW, my current policy -- adopted only a few months ago -- is to use only
> synthetic oil, change it on the specified intervals, and change the filter
> TWICE that often.  The specified interval may seem kinda long to some (6000
> miles on the Jag, 7500 miles on the Hondas), but that's why I use synthetic;
> another possibility I considered was using normal oil and changing twice as
> often.

My current thinking as well.  I had been using BP 3000 semi-synthetic at
17 UK pounds for 5 litres.  Mobil 1 was 26 pounds for 4 litres.  Regular
BP 20W-50 is 10 pounds for 5 litres.  

Aprox oil cost for a service (~8 litres):

Mobil 1			52
Semi-synthetic		27
Regular 20W-50		16

I could easily afford a number of regular 20W-50 oil changes compared to
synthetic.  Or should I stick to semi-synthetic and try to get the best of
both worlds - apparently unlikely if you believe Mobil. Re-jigging the oil
service interval seems a sensible thing to do but the choice of oil and when
to change the filter will make an impact.  

Any other options/opinions?



Cosmo
--
83 XJ6 4.2L
65 Mustang 289

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Follow-Ups:

• Re: Synthetic Oil
• From: "Kirbert" <palmk@mailer.gadcomm.net>

References:

• Synthetic Oil
• From: "Kirbert" <palmk@mailer.gadcomm.net>

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