Dear List,

Unlike some folks on the Samba who like to speculate and draw
conclusions from late night reruns of Mr. Wizard's World or
howitworks.com I usually try to research things that I am interested in
a little better.  One of the ways I do this is by going to an actual
professional in the field and asking them a few questions.  I feel that
these folks know about this issue much better than we ever could since
the company that they work for has invested millions of dollars in
research and thousands of man hours in studying these issues.  After the
discussion from thesamba about long stainless steel pipes leaked onto
this forum (pun intended) I took it upon myself to write a letter to the
folks at Prestone to see what they would have to say on this matter.
Here is what I wrote and also the response from Prestone tech person.
No animals were injured in the writing of this email:

Dear Prestone folks,

I have a question about using your antifreeze in a coolant system with

many different types of metal.  I currently run an automotive repair

shop where we deal with Volkswagen Waterboxer engines.  These are older

engines from the 80s and 90s, and since they are a flat four type of

engine the coolant system consists of a blend of aluminum, magnesium,

steel, cast iron, brass, rubber, and plastic.  Lately we have been

replacing some of our coolant pipes with stainless steel so that is in

the mix as well.  Many people tell me not to use the stainless steel

pipes in the coolant system because stainless steel has a high galvanic

voltage and this is going to cause more corrosion on the inside of the

engine or in the cooling system.  I feel that if you have a good

antifreeze, like your Prestone product, and you replace it every few

years with fresh coolant, that it doesn't matter what the galvanic

voltage of the different metals are, the antifreeze will keep the engine

from corroding on the inside.  Since you folks have obviously done

millions of dollars worth of testing on this subject I thought I would

ask your opinion on the subject.  Do you think there is any validity to

the idea that using stainless steel coolant pipes in a coolant system is

going to cause any more corrosion issues if the antifreeze is good and

working properly?

I await your advice and help
Ken Wilford

_Response:_

Dear Ken,

Thank you for contacting Prestone.

Modifications of the original system could cause unintended problems and
should be monitored closely.

In general, if they are not in direct electrical contact (e.g.,
physically in contact) with other metals, stainless steel parts in
engine cooling systems are typically quite harmless and will not cause
galvanic corrosion of other metals. Due to its high resistance towards
corrosion, stainless steel tends to generate little or no corrosion.

If a stainless steel pipe is used to replace a coolant pipe that is made
of a different material in the engine cooling system and the stainless
steel pipes are in direct physical contact with other metal parts,
galvanic corrosion may occur. The extent of the galvanic corrosion and
whether the corrosion damage is observable depend on system conditions
and coolant corrosion protection performance. If stray current corrosion
conditions are not introduced by the installation of the new stainless
steel pipe, and the coolant corrosion protection performance is not
compromised (e.g., good quality coolant is in use), excessive galvanic
corrosion of the parts made of metals such as aluminum alloys, carbon
steel, and cast iron in contact with the stainless steel pipe is
unlikely to occur.

We also apologize for the delay for any inconvenience this might have
caused.

Regards,

Jake Mathews

Prestone Technical Services

You can gather from this what you wish.  To me it seems to say that
unless a stainless steel pipe is in direct contact with an aluminum
part, then corrosion is very unlikely.  Also, even if this is the case,
if you have good antifreeze in place, this should stop this from
happening.  Of course you should continue to monitor the state of your
cooling system and refresh your coolant at regular intervals.  That is
just good PM.  Hope this helps.

--
Thanks,
Ken Wilford
John 3:16
www.vanagain.com
Phone: 856-327-4936
Fax: 856-327-2242