I have a 1992 Toyota Camry; my owner's manual says that ethylene
glycol
is the coolant.  I have a service receipt from garage work of a couple
years ago that says "BTBC Coolant" was added.  Is that Ethylene
Glycol?  I need to add
coolant and want to be sure if i add the red/orange/pink stuff
(ethylene glycol according to Kragen's) I will not be mixing with a
different anti-freeze.

tonychristopher...

It is most likely ethylene glycol...
The newer, more environmentally friendly,
antifreeze is propylene glycol.

According to this page, on autos.yahoo.com:
"Though some auto makers were initially cautious
 about using PG when it was first introduced, GM
 has now said that propylene glycol may be used
 in GM vehicles without voiding the manufacturer's
 warranty coverage and will perform adequately
 under most vehicle operating conditions. Most
 vehicle manufacturers, however, don't currently
 use PG as a factory-fill antifreeze because of
 its higher cost (about $1 more per gallon at
 retail)."
http://autos.yahoo.com/repair/results/ques012.html

Perhaps the receipt shows the price to be higher
than regular antifreeze? Or is the garage local?
Perhaps you can call them and ascertain what
BTBC might be. Since your owner's manual calls
for ethylene glycol, it is very likely that this
is what the garage used in your car. It would be
very unusual for them to add propylene glycol
without asking you or without you having asked.

A search for BTBC in conjunction with coolant turned
up no connection, so it is uncertain to what these
letters refer...perhaps a brand name?

The color may not be informative either, per this page
by Lorne Goldman and Herbert Pasveer:
"The likelihood of color confusion and unidentifiable
 mixtures is considerable among consumers and
 professional installers alike. The dye color used in
 coolant traditionally used to signify the type of
 antifreeze, but that's no longer the case."
http://www.gomog.com/allmorgan/coolantcolors.html

They also state that mixing antifreeze is not a good
idea, however they note that the coolant system should
be flushed every 2 years anyway. You state that the 
receipt is from a couple of years ago.

Therefore, although it is very likely to be ethylene
glycol currently in your radiator, it would be wiser
to simply flush the system and add new coolant of 
your choice. The page from autos.yahoo.com, above, 
discusses the relative merits of ethylene vs propylene
glycols.



Searches done, via Google:

BTBC coolant
://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=BTBC+coolant

ethylene glycol
://www.google.com/search?num=50&hl=en&lr=&ie=UTF-8&oe=UTF-8&safe=off&q=ethylene+glycol

ethylene glycol btbc
://www.google.com/search?num=50&hl=en&lr=&ie=UTF-8&oe=UTF-8&safe=off&q=ethylene+glycol+btbc

ethylene glycol tbc
://www.google.com/search?num=50&hl=en&lr=&ie=UTF-8&oe=UTF-8&safe=off&q=ethylene+glycol+tbc

ethylene glycol btb
://www.google.com/search?num=50&hl=en&lr=&ie=UTF-8&oe=UTF-8&safe=off&q=ethylene+glycol+btb

ethylene glycol bt bc
://www.google.com/search?num=50&hl=en&lr=&ie=UTF-8&oe=UTF-8&safe=off&q=ethylene+glycol+bt+bc

ethylene glycol btb
://www.google.com/search?num=50&hl=en&lr=&ie=UTF-8&oe=UTF-8&safe=off&q=ethylene+glycol+btb

ethylene glycol btb tbc
://www.google.com/search?num=50&hl=en&lr=&ie=UTF-8&oe=UTF-8&safe=off&q=ethylene+glycol+btb+tbc

antifreeze ethylene glycol btb
://www.google.com/search?num=50&hl=en&lr=&ie=UTF-8&oe=UTF-8&safe=off&q=antifreeze+ethylene+glycol+btb

"how to tell" "ethylene glycol" "propylene glycol"
://www.google.com/search?num=50&hl=en&lr=&ie=UTF-8&oe=UTF-8&safe=off&q=%22how+to+tell%22+%22ethylene+glycol%22+%22propylene+glycol%22

Please do not rate this answer until you are satisfied that the 
answer cannot be improved upon by means of a dialog with
the researcher through the "Request for Clarification" process.

sublime1-ga

---

Request for Answer Clarification by tonychristopher-ga on 26 Nov 2002 21:42 PST

should i be able to tell by looking at the color of the water in the
coolant overflow?  If I am still not sure which type antifreeze is in
my system, is is better or worse to top off the coolant system with
just water until i have it serviced/flushed (assuming i don't go into
any freezing weather environments)?

---

Clarification of Answer by sublime1-ga on 26 Nov 2002 22:09 PST

tonychristopher...

No. As I quoted from the page about color
by Goldman and Pasveer: 
"The dye color used in coolant traditionally
 used to signify the type of antifreeze, but
 that's no longer the case."

The two most used colors in North America
are orange and green, but the color will 
not positively identify the type.

And, yes, if you can top off the coolant with 
a quart or less of water, you should be fine
(barring freezing weather) until you have it 
serviced. *Note* Despite what conventional
wisdom says, it is better if you can use
distilled water, which is less likely to 
promote corrosion and rust than tap water -
especially in a mix with decreased antifreeze.
Distilled water is inexpensive, and available
by the gallon at your local grocery store.
Topping it off is much preferable to running
with a lowered level of fluid.

Complete answer that addressed all the explicit aspects of my question
and the implicit aspects of my situation.  Thanks!