JBPorscheOwner

I am posting in this forum because I have a black 2011 Porsche Cayenne S that uses Porsche coolant. My Porsche has NEVER had any coolant-related issues. However, I also have a black 1990 Cadillac Sedan DeVille (typically stored in my garage) with an aluminum engine block and heads that has 260K gently driven miles on it. I have owned the Cadillac since it was brand new, it is still in near-showroom condition, and there is nothing mechanically wrong with it. The Cadillac's very cushy seats are also much more comfortable than my Cayenne's 14-way adjustable seats so I always drive the Cadillac on road trips (its like sitting on a couch). In fact, senior Cadillac mechanics have told me that the original genuine Cadillac factory's (not GM's) seats are the most comfortable car seats ever manufactured.

However, my 1990 Cadillac's water pump (and all of the subsequent replacements over the years) have never lasted more than 50K miles. My local, very senior Cadillac technician told me that GM's water pump design for the 1990 Cadillac was the vehicle's primary weakness and that, in his experience, ALL 1990 Cadillac DeVilles' water pumps wear out and start leaking between 40-55K miles. Removing and replacing the Cadillac's water pump is a very expensive endeavor ($1500 or so). I have also learned that it is also very difficult to replace the Cadillac's water pump in a way that does not also create new oil pan and/or water-pump-area oil or water leaks. The Cadillac's oil pan and water pump were reportedly not designed with a sufficient number of bolts to consistently and uniformly tighten their gaskets. I last replaced my Cadillac's water pump (and coolant) almost two years ago. Thus, it is now time to change the Cadillac's engine coolant,

My question is, can Porsche's anti-freeze be used instead of GM's anti-freeze to BETTER protect the Cadillac's water pump?
If so, will the Porsche anti-freeze last longer than GM's anti-freeze? GM says their anti-freeze should be changed every two years.

I look forward to receiving a knowledgeable response from anyone who knows Porsche and GM engine coolant specifications! :-)

justabout

Sorry not a coolant expert but a friend has had numerous older Cadillacs 90s and 2000s and never mentioned a problem with water pumps, only coolant loss from the porosity in the block. Needed to add special GM sealer to the coolant periodically. It’s a shame they don’t upgrade the replacement part.

991Targa4S

NEVER MIX PINK AND GREEN COOLANT!!!

It will turn to wax and likely total the car.


I’ve seen someone do it. Please look it up!!!!!

JBPorscheOwner

To clarify, it if is safe (and better) to use Porsche anti-freeze vs. GM anti-freeze, my intent would be to complete flush the old GM anti-freeze out with distilled water before adding Porsche anti-freeze.

JBPorscheOwner

Thanks, but my 1990 Cadillac's aluminum engine block and heads do not have any porosity problems. Perhaps GM vehicles (not the original genuine factory Cadillacs) had porosity problems in later model years. The only problem with the water pumps from the 1990 Cadillacs I am aware of is that they generally do not last more than 40-60K miles before they start leaking. One senior Cadillac technician told me GM designed the 1990 Cadillac's vehicle's water pump in a way that created three places where it could fail over time.

schernov

so your Cadillac is pre Dexcool. I would recommend flushing the system and using BMW / MINI blue coolant. It's $20 a gallon at the dealer. That's full strength which needs to be mixed 50/50 with water.
If you want to read a lot of info about various oils a d coolants go to bobstheoilguy.com