Smasher

iTrader: (2)

I have 7 quarts of 10w30 Royal purple Synthetic.

$5 bucks each or $35 takes all 7

BashaZ

iTrader: (5)

why 10w30? arent we supposed to be using 5w30?

$5 is cheap though!! I usually get mine for $7

Smasher

iTrader: (2)

10W30 will be fine unless it gets really cold (-20) then you would want the 5w for cold start up.


Edit charts didnt post so see link, https://my350z.com/forum/engine-and-...-and-info.html


What does the oil weight actually mean?
An oil’s weight refers to it’s measured viscosity at a given temperature. The temperature of the oil is important when measuring it’s viscosity because an oil becomes thinner, or less viscous, when it is heated. Conversely, oil becomes thicker, or more viscous, when it is cooled. Because oil viscosity changes with temperature, an oil’s weight is determined by the measured viscosity at a specific temperature (100 deg C). The unit of measure is called a centistroke (cSt). The higher the measure of viscosity at 100 deg C in centistrokes (cSt), the higher the oil’s weight. The following chart shows the viscosity an oil must be at a given temperature for each oil weight.


So how does that translate into the weight I see printed on the bottle, like 10W-30?
Some oils are straight weight oils, like a straight 30 weight oil. This means the oil is always a 30 weight oil at any given temperature. The oil still thins out with heat, and thickens up as it cools, but at any given temperature it will measure within the specs for a 30 weight oil at that temperature. This is not good for your engine during cold starts or in cold weather, because a 30 weight oil is very thick when it is cold. Thick oils are harder to pump and therefore don’t flow through the engine and lubricate very quickly. The solution is a multi-grade oil. A multi-grade oil is still thicker when it is cold than when hot, but not as thick as a straight weight oil. In the case of a 10W-30, the “10” refers to the oil’s “Winter” weight (hence the “W”). A 10 weight oil is thinner than a 30 weight oil at cold temperatures, and thereby flows easier to properly lubricate the engine upon start-up. As the engine reaches operating temperature, the oil thins out- but does not stay a 10 weight oil. It becomes a heavier weight, and in this case, becomes only as thin as a 30 weight oil at operating temperature. Here is a simple chart, courtesy of Noria, that shows how a 10W-30 compares to straight 10 and 30 weight oils.


What winter weight should I use, a 5W, 10W.. etc?
Since the majority of engine wear occurs during start-up, it is important to use oil that will flow well and lubricate the engine quickly during this time. Remembering that oil is thicker when cold, the proper winter weight is one which provides the maximum amount of flow for the given ambient temperatures when the engine is started. The colder the temperature of the oil, the harder it is to pump, so a thinner winter weight is beneficial during start-up. As ambient temperatures increase, the oil will thin out and start to get closer to its operating grade, and at some point, multi-grade oils like 5W-30 and 10W-30 will be close to the same viscosity for a given ambient temperature. This means that there is no harm in using 5W oil even in hot climates. As an example, the start-up viscosity of a 5W-40 and a 15W-40 may well be the same if the ambient temperature is hot enough. This also means that heavier winter weight oil (such as 15W-xx) may be used if the ambient temperatures are warm enough to ensure that it can be pumped quickly enough to properly lubricate the engine during start-up. The importance of selecting an oil with proper start-up viscosity is paramount, and is why auto manufacturers recommend winter weights based on the ambient temperatures with charts similar to this one:

Smasher

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