Daniel J. Stern wrote:
> On Thu, 21 Jul 2005, Alex Rodriguez wrote:
>
>
>>>5w20 is being recommended by lots of automakers in their North
>>>American-market vehicles for fuel economy certification reasons. The
>>>same engines in the same cars often call for 5w30 in other markets.
>>>This does not mean older vehicles should be switched to 5w20.
>>
>>This sounds reasonable. But I would say it is not working. My T&C with
>>a 3.8 engine gets horrible mileage in city driving, under 15mpg. On the
>>highway it does ok, about 24mpg.
>
>
> Not the point -- the point is to squeak another fraction of an MPG in on
> the Federal fuel economy and emission certification tests, NOT to offer
> the consumer measurably better on-road fuel mileage.

And way secondary to the squeezing of another fraction of an MPG is
improving engine life. Not that it will necessarily lead to
catastrophic failure or gross reduction in useful life, but there is
bound to be incremental cost in engine life. IOW, will they do put
value on engine life, when they get an opportunity to trade off a
miniscule gain in MPG for slight or moderate loss in engine life, they
will take it. Compare that the manufacturer's recommendations in
countries with similar ambient temperatures that don't have CAFE rules
are for thicker oils(we're talking similar vehicle/identical engine.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
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