W does indeed stand for winter, although it's a bit misleadng. Above post provided some good info. Oil is a tricky thing.
Bobistheoilguy is a great site

 

You can lead a horse to water but you can't make him THINK...

 

In this paper there's some historical stuff on the Winter grades:

http://www.ideas4ag-ed.com/uploads/3..._viscosity.pdf

 

I never really knew this so I looked it up. I assume Valvoline is an authority.

http://www.valvoline.com/faqs/motor-...and-viscosity/

Also, in my experience whenever someone scoffs at the use of Wikipedia, they are almost always wrong.

 

A single-grade engine oil, as defined by SAE J300... has established eleven viscosity grades, of which six are considered Winter-grades and given a W designation. The 11 viscosity grades are 0W, 5W, 10W, 15W, 20W, 25W, 20, 30, 40, 50, and 60. These numbers are often referred to as the "weight" of a motor oil (Ed: but really are a measurement of the oil's viscosity.)

The SAE designation for multi-grade oils includes two viscosity grades; for example, 10W-30 designates a common multi-grade oil. The first number '10W' is the viscosity of the oil at cold temperature and the second number is the viscosity at 100 °C... an oil labeled as 10W-30 must pass the SAE J300 viscosity grade requirement for both 10W and 30.

 

So, based upon the previous partial quote from Wikipedia, the first number is the COLD viscosity (when starting in winter, for example) and the second number is the operating viscosity - both can be important if you live in a cold climate; but if you're in Southern California in summer, the hot viscosity (second number) is the only one that matters.

 

TIP: Attempt to use the specified weight oil that the manufacturer recommends for use in it's product for everyday general purposes. Extreme hot or cold climates can adjust accordingly.

 

When I bought my 02 TL, the dealer's service manager had a Q&A session for that month's new owners. One of the questions was whether to use synthetic oil. The manager asked each owner what was their last car and why did they trade it in or sell it. He asked by mileage with the lowest mileage first. Most were previous Honda or Acura owners. Some were over 150k and all were still running fine. Then he asked what oil they used and the service interval. Conclusion - conventional oil changed at the service interval will keep the engine running fine well past 200k.

I chose to go with synthetic knowing rationally it would only benefit the next owner, but it made me feel like I was treating the car better. And I could care less whether it was winter in the mountains or hot in the desert with synthetic.

 

Waste of time choosing between 5w30 or w20 either will do just fine. Want protection? How about full synthetic vs conventional?

How about Cheap brand transmission fluid vs Honda DW-1? This will save your life. LOL

 

Thats simply not true. Full syn has MANY advantages.

 

Point well taken since this is the 2nd gen site and the cars are now over 10 years old.

"If I'd known I was going to live so long, I'd have taken better care of myself"

 

Yeah, we all say that after we limped along from time to time.

Ha, hah.....cars are a bit easier to replace parts on ..... then on ourselves !!!

 

What does the "w" in a grade of motor oil stand for? The "w" in motor oil stands for winter. The first number in the oil classification refers to a cold weather viscosity. The lower this number is, the less viscous your oil will be at low temperatures.

 

W=Winter may well have been the original usage of the designation, but that doesn't really apply any longer; these days for all intents and purposes, the "W" means is the SAE "Weight" of the base oil as measured at non operating conditions (say 59°F). So, a 5W-20 is a 5-weight oil with enough stability (either due to pure carbon chains of synthetic base oil, or through viscosity enhancers for conventional oil, or some combination thereof) to only thin out to what a straight 20-weight oil would thin out to at operating temperatures (say, 212°F).