Hi All,
I had to weigh in on this one... many moons ago I bought my first car... a 1962 Plymouth with a slant six. The car had 147,000 miles on it, and smoked like a chimney cold. I eventually stumbled onto a product called Alemite CD-2, which was a honey-thick preparation that claimed to stop engine smoking. Added to a fresh oil change, it probably increased the oil viscosity 20-30 points, reducing the amount splashed on the cylinder walls and slowing the flow down the valve stems. Hardly any smoke cold, and none hot. In my case, on that car, it worked well.
Fast forward 30 years, and I'm working for a major auto manufacturer, with an assignment in Service Program Development. In an effort to incrementally increase fuel economy and reduce emissions (and we're talking real, real small increments) said manufacturer is recommending 5W-XX oils for vehicles used in cooler climates, and is experimenting with 0W-XX. The bean counters have done the math and figured that the increased warranty costs and hit on customer satisfaction are more than offset by the ability to sell more high-profit vehicles (read non-econoboxes) and still satisfy CAFE and state (read California) mandates. Hmmmm....
Our Imperials were designed for use with the recommended weight oils, period. Granted that the newer oils have better additives, etc... according to the owners' manuals these cars are meant to have 5W- oils in them only in temperatures colder than 10 below (F). That happens here in Michigan about once a decade (actual air temp, not wind chill), and if it's that cold, I'm not goin' out anyway! I can't imagine even Brad Hogg sees temps that cold very often... Brad?? Any other members further north???
On the other end of the spectrum, I run 20W50 racing oil in my 451ci Barracuda. I try not to run it at all below 40F, as the oil pressure goes sky high...(90-100 psi). I can't imagine that the top end gets any lubrication to speak of for the first minute or so. But it holds pressure well in high temperatures, and under "supervised acceleration trials" :) Even in 70 degree weather, I crank it to get pressure up before letting it fire, and run it at idle the first minute or two... and even then I'm still showing 70-80 psi - way too much for normal use. The car runs 40-50 psi once warm. The rule of thumb Chrysler gave us years ago was that 10psi per 1000 rpm is sufficient to prevent engine damage. Any more just consumes horsepower and puts unneeded strain on the oil pump drive.
I have a bad habit of jumping in the beaters (new cars) and as soon as they're lit, popping them in gear and heading for the road. I nearly always let the Imperials run 30-60 seconds and never have a problem. Well, the other morning, it was cool, and I needed to move the '63 Imperial to get another car out... I started it, lifted the park lever and punched the reverse button, and got the expected slow reaction from the transmission. It just reaffirmed in my mind that the old girl needs a few seconds to get herself gathered before we leave.
So IMHO, I'd stick with the recommended oils, using thicker oils or additives when dictated by age and wear, and then only when the weather permits.
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