Why does the data sheet show the Low temp viscosity as <7000@-25C???
Why don't they give a real value instead of the API limit??? Hard to compare oils without any real data here.
I think Chevron and Mobil data sheets give "real" numbers.
quote:Originally posted by JonS:
They just have to meet the spec to be called a 5w or 10w. Why should they go more than expected, unless they want to make a better oil. They just do the bare minimum.
Yep, that's the problem with most OTC dino oils, they just meet the minimum specs. But yet if you took that same oil with 2000 miles on it, and ran those cold cranking tests then, it would no longer pass! Just another reason why you should use synthetics (or Schaeffer's blends) in the winter time if your area gets very cold.
The reason is the "actual" number doesn't really matter...ie. the cold crank viscosity falls within a range determined by API for a specific temperature. And it meets it....else it wouldn't be a 10w. It would be a 5w or 0w or even a 15w...you get the picture. In other words all 5 weights will be the same at a given cold temperature because they have to be. And that temperature is -30C.
The thing is that yes, they must meet a MINIMUM set by the API, but that doesn't mean they can't be better than the minimum.
All 5 weights are NOT the same at -30C. They all are at or less than the maximum allowed by the API, but they are NOT the same. Going through some data sheets will point that out in a hurry!
And some oils call themselves a higher w rating than the really qualify for, simply because some buyers a leery of buying an oil that is "thin" based on that number - One of the Schaeffers 15w40 oils is the one that comes to mind, if I am remembering correctly.