I don't think this type of product is quite as questionable as the supposed
"miracle" teflon additives, Slick50 and whatnot.  The CD-2 product works, I believe,
on the idea that noisy lifters may be caused by either gunked up oil passages or the
moving parts within the lifter being frozen with gunk.  The CD-2 type products, I
think, are just combinations of solvents and very light oils...something along the
lines of a liquid wrench concept.  It dissolves away the gunk and allows frozen
parts to move or dissovles away gunk blockages.  The question is do these solvents
and low viscosity oils damage your engine in any way by thining the oil or
dissolving internal parts that shouldn't be dissolved...i.e. gaskets, o-rings etc.
Anyway, that's my understanding....please correct me if I'm misinformed.
Mark

Jim Arnott wrote:

> Someone a couple of months ago suggested "CD-2" lifter rebuild in a can (I
> don't remember exactly which CD-2 product it was, but there's only one that
> claims to "quiet noisy lifters".)  This , of course engendered a bit of
> discussion about oil additives in general.  Having suffered from Vanagon noisy
> lifter syndrome for years, on a motor that will turn 180k miles tomorrow, I
> felt that I had v. little to lose.  I gave it a try.  It "quiets noisy lifters."
>
> Don't flame me.  It worked for the suggester, it worked for me.  If you don't
> think it's wise to put additives into your crankcase, DON'T!
>
> Jim Arnott
> WetWesties
> Union, OR