lalaMAX

did some search but no luck...
can someone teach me that what does "5w-30 stand for?
basically what is the difference between 0w and 5w and 10w?
and difference between 20, 30 and 40?
sorry if it's a repost.. just wanted to learn... thanx

Bonka

iTrader: (13)

Viscosity (IE: 5W30, 10W40) tells you the oil's thickness. Thin oils has a lower number and flows more easily, while thick oils have a higher number and are more resistant to flow.

I found this to be a good read:
http://www.carbibles.com/engineoil_bible.html

SilverMax_04

Interesting site, bonka. And the information there seems to be quite accurate.
But your explanation (in your post) is not quite correct. A multi-viscosity motor oil has two numbers (5W30 is what Nissan is currently recommending for the 6th Gen Max). This is a single motor oil which has the viscosity and flow characteristics of a single-viscosity 5 weight motor oil when it is cold (there is a specific temp, but I'm not certain exactly what). Then, when it is hot (another specific temp) it has the viscosity and flow characteristics of a single-viscosity 30 weight motor oil. This is why you don't see may single viscosity motor oils being sold today. The multi-viscosity motor oils are better performers over a wider temperature range.

Bottom line, the lower the first number the lighter the oil (and better flowing it will be) when cold. The higher the second number, the heavier the oil will be (and more viscous) when hot.

One warning, there are reports of some wide viscosity motor oils (0W40 or 5W50) experiencing shear, such that the upper viscosities do not maintain over use. They become effectively 5W30 or even 5W20 oils. Not pretty.

Guess I need to post more to answer the original question. Unless you live along or above the Canadian border, I would stay away from any multi-viscosity oil with a 0W__ rating. You need to see consistent early morning starting temperatures of -20 degrees F or lower to even consider a 0W__ motor oil. And then I would only run this light motor oil during the winter months. A 5W__ motor oil should be able to consistently handle early morning starting temps of about -10 degrees F.

I would not buy any motor oils with a __W20 viscosity rating as you will not get sufficient engine protection when it is hot. Through much of the US (except where the operating temps are consistently above 100 degrees F) you should plan on a __W30 motor oil. Use the __W40 oils when you see temps consistently above 100 degrees F. Because you will not see those high temps year-round, only run this heavier oil in the summer time.

I personally run (year-round) 10W30 Mobil 1 motor oil in my Max. (But here in Colorado, my Max sits in a garage that never gets below freezing in the winter.) I had a volume of 10W30 MObil 1 remaining from an older car. But I now believe the only reason Nissan recommends the 5W30 weight oil is to just slightly improve the gasoline mileage it can quote. Nissan in Europe reportedly recommends 10W30. I personally think I get better protection when the engine reaches operating temps (even though both oils have a __W30 rating).