Robert Davis is the guy that brought Bar's Leaks to the attention of Saab 9000 owners.  What he said made sense to me, so I started using the product and have become a vocal advocate for its use.  These cars have a history of heater core leaks, water pump seal failures and head gasket leaks.  With that sort of history, I certainly advocate the use of any preventive measure that doesn't do harm.  In my experience, Bar's Leaks (liquid, in the silver bottle) does no harm.  In Robert's experience, as well as a couple of others, it obviously does great good, because they have not experienced the typical 9000 cooling system leak problems over years of use.  Bar's Leaks recommends that you replenish every six months or 15000 miles, whichever comes first.  I absolutely recommend a coolant drain, backflush and refill every 24000 miles, including the Bar's Leaks treatment.

"My first impression was years ago in an owner's manual for a Suzuki motorcycle I once owned that insisted in no uncertain terms that BL be installed at every coolant change. Amazed that a Japanese company would be so insistent that owners use an American cooling-system additive that dates back to the '40's, I looked into it further, finding that Suzuki wasn't the only one. I tried it first, I think, in my '91 very early on after it exhibited the ubiquitous (for Saab) coolant smell apparently from a leaky heater core. The smell never came back and I had no further cooling system problems, including water pump, 'til I sold it two months ago at 124k. It goes in all my water-cooled vehicles whether they exhibit leak symptoms or not. It may be a quick, painless, inexpensive cure for the common heater core maladies that have plagued Saabs for years."    - Robert Davis

Robert has found that the following OEM's install Bar's Leaks in radiators at their factories:

Allis Chalmers (AGCO)
AM General (Hummer, etc.)
Carrier Transicold
Caterpillar (Canada and USA)
Cloverland (engine rebuilder)
Daimler-Chrysler (US, Canada, and International)
Engine Rebuilders (Canada)
Ford Motor Company (US, Canada, and International)
General Motors Corp. (US, Canada, and International)
Gopher Motors (engine rebuilder)
Isuzu (international)
Jaguar (international)
Komatsu (heavy duty)
Marshall (engine rebuilder)
Mitsubishi (international)
Navistar (International Harvester)
RB&W Logistics (industrial)
Subaru (international)

Bar's Leaks Web site