Re: synthetics

[John Graham <jgraham1@erols.com>]

Harrison Sapir wrote:
> 
> sad story here: before i knew any better, I added a quart of Castrol Syntec to my
> 5000tq when it was down a quart. not knowing that the chemicals in synthetic oil
> actively repel those of standard oil, I drove on. One mile later the pressure in
> the system blew up an oil return line on the turbocharger. Oh, sometimes you learn
> things the hard way.

There is a API standard that says that should never happen. I would call Castrol
about that.
 
> 
> Avi wrote:
> 
> > With the risk of getting some nasty messages from some of you, not so
> > "distinguished" listers, let me bring some important points to your attention:
> >
> > Std. oils (none synthetic) will not leave any more deposits in the engine
> > than synthetic oils, providing you change your oil under 5K miles and
> > fully warm up the engine (oil temp.), flushing the engine every second oil
> > change is a bit of an overkill, not quite sure what it does to seals life?
> > (maybe extreme cases?...), if i remember correctly the additive package on
> > the std. oil and synthetics are very similar.....
> > Avi
> >
> > Please, do away with nasty messages, if anybody want's to comment, it
> > should be to the point and not personal.......even about "synthetic oils"
> >
> > At 11:58 PM 12/30/97 +0000, you wrote:
> > >Sargent Schutt wrote:
> > >>
> > >> John Graham wrote:
> > >>
> > >> > > It would be interesting to compare your engine oil consumption over the
> > >> > > next few months with your pre-synth days. I made exactly the same
> > >> > > changes as you on my 91 200q about 5k miles after I bought it, and
> > noted
> > >> > > that with the change to synth my car started burning oil (1/2 qt per 4k
> > >> > > miles). Since then I've switched to dyno engine oil (20/50) and have
> > >> > > noticed less oil consumption. This all due to the detergent effects of
> > >> > > the synth engine oil.
> > >> > But were you useing a 20W50 synthetic?
> > >>
> > >> Yes.
> > >>
> > >> > >
> > >> > > In the tranny, I originally put in Mobil 1
> > >> > Bad move. Mobil 1 is a GL-5, even Mobil says don't use it in a
> > >> > Quattro.
> > >>
> > >> Hmm, the Audi tech said the mobil-1 tranny oil he put in was the
> > appropriate
> > >> weight. Sure was dirty when I changed it 20k miles later, though (to the
> > >> Redline).
> > >Mobil-1 gear oil is GL-5 and is corrosive in a Quattro tranny.
> > >Redline MT-90 is a GL-4 and is ok.
> > >>
> > >> > > ( at143k miles, made an
> > >> > > improvement), then recently changed to Redline - BIG improvement in
> > >> > > shifting with the Redline. I highly recommend it.
> > >> > >
> > >> > > Anyway, keep me posted (the list) as to the change in oil consumption
> > >> > > levels (if any) you see in the coming month or so.
> > >> > >
> > >> > Make sure it's the same grade oil like 20W50 dyno to 20W50 synthetic.
> > >>
> > >> Why should it matter as long as the weight is appropriate to the outdoor
> > >> temperature? That would seem to be the important thing. Regardless, the
> > >> detergents in the synth clean out the buildup that has become part of the
> > >> motor (after high, 100k + miles), particularly after 140+k miles when I
> > >> switched. (currently 167k miles), That's is what I'm after here. More proof
> > >> of that phenomenom - I have heard about it, I experienced it; How many more
> > >> out there?
> > >>
> > >Because synthetic oils don't act the same as reg. oil under pressure.
> > >A 5W30 synthetic may look like a 5W40 reg. to hot runing engine.
> > >You don't need more proof of the phenomenom because it's true.
> > >But it's the why. Just how much gunk doe's one let build up in the engine?
> > >I my old days before synthetics, I use an engine flush every other oil
> > change.
> > >Because you don't want oil pump by pass valve to get stuck.:-(

John
1990 CQ