I'm due to change out coolant. I've read threads stating that your engine will get better cooling running "water wetter" and higher ratio or water to coolant,ie, 60/40.

The mgr at Jiffy Lube says the opposite is true---they say to run their premier mix of 80/20, coolant/ water, for optimal cooling. Says high ratio of water will just boil quicker.

What should I do?

50/50 i think is considered optimal for all around purposes and is available in premixed containers everywhere. the 99 owners manual states to stay between 20 to 60%. lower than 20% antifreeze may lose anticorrosion effects (and lube for water pump) and over 60% loses cooling ability. also states to use whatever ratio is needed to protect to -33F and suggests refill/topping off when needed with 50/50.

personally, i keep it at 50/50 and use prestone, but may change to the more environmentally friendly type next time.

many go the extra step and use distilled water.

Whatever type of anti-freeze you buy, read the jug that
it comes in. It will tell you what percentage to mix
for what temperature range you normally operate in.
Generally, a 50/50 is perfectly fine for most environments.

Sounds more like a way to optimize their profit. Ask him to show you some written research that proves it. Otherwise stay with the 50/50.

A higher concentration of coolant vs water is actually less able to keep your engine temp down. I'd go back to Jiffy Lube and ask the manager what is so special about their antifreeze that makes it work differently than all the others. <img src="/forums/images/graemlins/lol.gif" alt="" /> I'd stay 50/50.

There's nothing special about antifreeze...it's just a solute (spelling?). Anything dissovled it water will lower the freezing point and elevate the boiling point. Ethylene glycol is used because it's mostly compatible and non-corrosive with the metals, rubber seals/hoses, gaskets, etc. used in engines. You could use sugar or salt...but I doubt your cooling system would last. 80/20 sounds like too much solute (why does that sound wrong?...it's late) and not enough solvent. At what point does it become too much? Not sure...

A solute "can" be correct.
A solute is generally a component of a solution in lesser
quantities than the rest of the components that make up the solution.

For my warm climate I use about 30% anti-freeze and about 1/3rd of a bottle of this stuff http://www.honeywell.co.nz/business/holts/prestone/sar.html to make sure enough anti-corrosion and seal lubricants are in place. The rest is purified water.

...not to change the subject, it's sorta relevant...

what might be the adverse effects on using NOT distilled?
I'm thinkin' of using distilled next flush/fill, bcuz I've noticed what appears to be some kinda "salt" floating around in the reservoir. I filtered it through a coffee filter, and when dry, it's like grayish talcum powder. Wonder if this is something precipitating from the well water (with water softener), of if it's like Alum Oxide from the aluminum of the head ?

Anybody else seen this ? p.s. I'm running 50/50 ...

That's most likely calcium... and that's exactly why you
should use distilled water. It plugs up the rows and passages in the radiator.
Minerals in regular tap water do all kinds of funny stuff.
They aid in corrosion, which anti-freeze has inhibitors for,
but it can only do so much. They also increase the boiling
and freezing point of the water. Not enough to worry about, but they do.

Nothing wrong with using tap water, you just need to
do coolant changes and flushes a little more often than
you would with distilled water.