While this is written for SAABS, a lot of it applies to any motor. I'm using the Mercedes Benz factory coolant on my SAAB with no problems. It's $10/gallon, so not all that more than Wal-Mart specials.

Hope this helps.

-Dan

COOLING SYSTEM SERVICE SAAB 900 and 9000
>  COOLANTS  Engine coolant should be maintained to promote both its
>effectiveness and the longevity of the engine and the entire cooling
>system. Over time, and with those occasional top offs, the coolant becomes
>unknown and begins to break down. Phosphates and silicates and produced
>aluminum oxides fall out of suspension building up and promoting
>electrolysis, pitting of the aluminum surfaces and the main gaskets and
>seals. The deposits of these phosphates and oxides in the layers of the
>head gasket splits it like ice in pavement. Concentration becomes unknown
>and thus its freezing point unknown. Mixing common ethylene glycol and the
>newer, supposedly environmental friendly, propylene glycol, produces a mix
>with a specific gravity unreadable by ball drop type testers meant for
>either one or the other of the coolants. Use one or the other, but do not
>mix. Because of this, you might want to keep a little of what you're using
>around, just in case.   We have found increased life and fewer failures of
>any kind in the cooling systems after using Mercedes Benz factory coolant.
>It is phosphate free and pH buffered with inhibitors to aid in the
>prevention of electrolysis. When servicing cars that have been using it,
>the difference in the appearance of the internal cooling system is
>noticeable. Upon thermostat replacement, the aluminum is not covered with
>the white aluminum oxide or pitted from electrolysis as is common with the
>green coolants routinely used by some.   The coolant of your choice, unless
>it specifically states otherwise on the container, should be kept at the
>least concentration necessary to insure proper cold weather protection for
>its expected needs. As close to a 50% coolant to water mix as you can get
>is best, as long as the coolant's label's freezing point chart is followed
>to insure adequate protection. Running pure coolant is not a very good
>idea, more is not better. Particulates are more apt to form at higher
>concentrations.   We service the cooling system on our customers cars every
>30K miles with a drain, a flush, a thermostat replacement, a tightening of
>all the cooling hose clamps, pressure test for leaks, inspection of all
>hoses and replacement of any upper hoses (top radiator and bypass hose at
>rear of head) that are over three years old, fan operation, coolant refill
>and relay upgrades.      THERMOSTAT (Look here for more info and pictures)
>Thermostats are considered a maintenance item in our book. They operate by
>use of a fixed volume of wax that expands a calculated amount at certain
>temperatures, pushing them open. Each cooling system cycle works the
>thermostat, exposing it first to temperatures above what it is set to open
>at, then, after it gets hot and opens, it is flooded shortly with much
>cooler water, so it closes. It oscillates between open and closed as the
>engine is driven to maintain an even cooling system temp. The thermostat
>works more than its commonly perceived opening once per trip. This wears
>them. You can see evidence on the brass bodies of thermostat where they
>begin to cock and bind in their travel. Let them catch here just once, and
>it could take out the engine. While you are examining the thermostat, look
>at the top of it, where the chamber holding the wax is sealed. Most older
>thermostats, failed and not yet failed, show evidence of leakage of the wax
>here. Since that wax is calculated in its volume and expansion rate, any
>leakage changes its properties and amount of opening. Overheating by
>running low of coolant can subject the thermostat to much higher than
>normal temps which could rupture its seal and allow the wax out, or
>overheat the wax to the point it changes in its character. Anytime the car
>overheats, I would consider replacing the thermostat, the trust is gone.
>The thermostat in a 900 sits under the housing that the upper radiator hose
>attaches to on the engine. 8 V's have easy access via two 13 mm bolts. 16
>Vs' require the removal of the AIC valve to service the thermostat. Unplug
>the valve, remove its two hoses, and then remove the 10 mm bolt holding it
>in its bracket. Set it out of the way (now would be an excellent time to
>clean its shutter wheel with carb cleaner). Now you can remove the two 12
>mm bolts holding the housing and access the thermostat. On a 9000, the
>thermostat sets on the rear of the head on the driver's side, still under a
>housing to which the upper radiator hose connects, more of a task to access
>than the 900s though. There are various things attached to this housing,
>from fuel pressure regulators with their 4 mm Allen's to DI ground wires
>and brackets on later 2.3 engines with 4 mm Allen's or 10 mm bolts. Often
>it is time and knuckle saving to remove at least the rubber bellows going
>to the throttle housing. 2.3's require removal of some throttle housing
>hoses to get to the thermostat so that it can be accessed and cleaned
>properly on the mounting surfaces.  On cars with a rubber seal for the
>thermostat gasket (all except the early 8 Vs), clean the housing surfaces
>with a brush. No sealant should be necessary for the gasket. Make sure that
>the bolts are clean, wire brush their threads and use an anti seize
>compound on them to prevent future troubles. Install the thermostat so that
>the brass air bleeder valve on it is at the highest point. Turn the lower
>plate so its hole is in alignment with the brass fitting hole. On 16 V
>thermostats, turn and position the hole in the bottom plate to align with
>the bleeder on the top of the thermostat. This allows all the air to leave
>the system. Though the 9000 has no bleeder port to the exterior, its
>thermostat design allows it to empty air to the reservoir, if the
>thermostat is properly aligned.   Use a factory thermostat. In all but the
>coldest climates, we recommend the 82 degree Celsius thermostat under the
>part number 8817538 for 16 V engines. The 8 V has its own thermostat,
>number 9337551. Do not install a 8 V thermostat in a 16 valve engine. The
>16 V has a special design and it is for this reason also that we don't
>recommend aftermarket thermostats.  Too much depends on such a relatively
>inexpensive part. The three position design of the Saab thermostat allows
>proper operation of the cooling system. Some attempts at copying it have
>resultedc in overheating or loss of cabin heat when the car gets warm.
>Either requires doing the thermostat again, so why not go ahead and put
>what was designed for the car there, not just one that fits the hole.
>COOLING FANS  Check the operation of the cooling fans. On 900s, the sensor
>is in the upper left hand corner of the radiator with two wires connecting
>to it. Disconnect the two wires and touch them together. With the key on,
>both fans should run. 91 and up 900 S's should be checked for the
>modification and replacement of the cooling fan relays if only one fan
>runs.  < CONTACT US FOR DETAILS> LOOK HERE FOR WIRING INFO >> cars, the
>modified relay is both less expensive and more reliable than the relay that
>is there.   To check the high speed operation on equipped 9000s, first
>engage low speed as above and then remove the relay in position F of the
>same fuse box and jump the 1 pin (+30) to both the 2 (87) and 3 (87B)
>terminals. This should generate warp drive captain. If the fuses for the
>cooling fan haven't been updated, change them to 30A in the fuse box under
>the hood, as per factory bulletin 03/89-1127 Running Change Upgraded Fuse
>For The Cooling Fan.   For all 900s and Early 9000s with the two wire fan
>sensor, we strongly suggest you swap the original fan sensor that turns the
>fans on the first time at 92 degrees Celsius for one that turns them on at
>82 degrees. When used with a factory 82 degree thermostat(8817538), this
>avoids the temperature overshoot problem seen when getting in traffic after
>highway driving, and maintains the gauge reading at about halfway. The
>sensor simply screws into and out of the radiator and the wires plug right
>up. We use a sensor made by Wahler for VW. You can get this sensor from a
>VW dealer under the part number 823959481D, or from us if you can't find
>it. That is a pretty old VW part number now, but it is what we order it
>under. We have not found a cooler direct replacement for later 9000s with
>the two stage fan, but are searching. You can rewire them to accept the
>cooler old style switch, but that is detailed in another page on this site.
>     FLUSHING, FILLING, BLEEDING  To flush the cooling system, find a
>suitable pan to catch the old coolant. Drain it first from the radiator
>drain. Be careful if the petcock seems tight not to damage the radiator. On
>900s, the drain is on the right lower front of the radiator. Early ones
>have a 17 mm petcock with a 22 mm support hex. Later ones have a 24 mm
>plastic petcock. 9000s' have a petcock accessible from the bottom on the
>right side. They are hard to get to without removing the under panels and
>can become brittle and break. You might find it easier to remove the bottom
>hose on the water pump, below the AC compressor.   Make sure on cars with
>manual heat controls, that the temperature selection on the heater is set
>to hot. This opens the hot water valve and allows the flushing of the
>heater circuit and core. On 9000s, the heater circuit is open all the time,
>there is no need to set the temperature. After the most of the old coolant
>has drained, open the heater circuit by removing a heater hose and
>inserting a garden hose.Then you can proceed to flush the system by running
>water through the system until it comes out clear. This can take up to an
>hour. On a 900 with an 8 V engine, we remove the coolant hose running to
>the center of the intake and flushing through it into the heater. On 16 V
>900s, remove the hose coming up from behind the AC compressor off a pipe
>running to the front of the head, flush through the end of that hose. On
>the 9000s' removing the smaller hose connecting to the rear of the head
>(facing the left side of the car) allows its heater core to be flushed
>through that hose. We flush the systems with the thermostat removed and
>replace it when finished. Swapping the point at which you place the garden
>hose, from the initial heater hose for the majority of the heavy work, to
>the reservoir to rinse it and its hoses, to the top radiator hose, anywhere
>you can stick it in the open system, will make sure no old coolant gets
>left lying around. When it all looks nice and clear, let the engine drain.
>Then shut up anything you have opened, getting the system ready for its new
>coolant.   Pour in the required amount of coolant, making sure to leave the
>manual heat controls on hot. On a 900, there is an air bleeder port on the
>thermostat housing. It has two 11 mm (7/16") hexes. Hold the lower one and
>loosen the top one to allow trapped air to escape the system. Fill with the
>coolant/water mixture until the reservoir is to the max line on 9000s and
>until a steady stream of coolant comes out of the air bleeder port on a
>900. Then shut the bleeder port on a 900 and fill to the max line of the
>reservoir. Check for leaks. Then start the car and let it idle. Pay
>attention to the reservoir. If air comes up (it will), re adjust the level.
>Run the car until the fans cycle once. You might want to reopen the bleeder
>screw on a 900 after the car runs a few minutes just to make sure there is
>no trapped air. After the fans cycle, recheck and adjust the level at MAX
>if necessary. Replace the radiator cap and run the car until the fans cycle
>again and shut it off. Let it sit for 15-20 minutes and check for leaks
>after the system builds all the pressure it should. After a complete cool
>down, recheck the level. Do this again just to be sure after another
>temperature cycle.   4     Attachment Converted: "c:\eudora light
>3.05\attach\ymason.vcf"