Question on BMW 3-Series E36 Coolant Flush

After doing extensive research on coolants, there seems to be nothing particularly special about the product directly available from BMW. The p-glycol is a bit more expensive, but less toxic and as the article pointed out doesn't provide as good low temperature protection. The e-glycol Prestone product is phosphate/nitrate/borate/silicate free and clearly suitable for any aluminum based engine and/or radiator which may contain other metals or plastics. As to the phosphate issue, that seems to only be a problem if hard water is used. With distilled water there should be no problem. And while there have been some comments about distilled water tending to absorb CO2 and becoming acidic, this mild acidity would be more than compensated for by the coolant basic additives.
With regard to the thermostat, is the rotational orientation of thermostat primarily important for smooth coolant flow over the two supporting prongs going to the center ? It would seem the optimal orientation would be to have a line between the prongs parallel to the coolant flow. Is this correct? Or does the orientation have something to do with the thermal operation of the thermostat?

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This post was auto-generated based upon a question asked on our tech article page here: Pelican Technical Article: BMW 3-Series E36 Cooling System Flush

[Nick at Pelican Parts]

Thermostat orientation is usually determined by a vent hole at the top of the thermostat. This usually leaves the supports parallel with the ground.

I stick with BMW coolant, but each available coolant has strengths and weaknesses, choose the coolant you are comfortable with.

- Nick