Most engine wear occurs at a cold start when the oil is thick and gooey and the oil pump has trouble getting it flowing. Plus, when the oil is cold and thick, it bogs the crank, and your starter has more trouble turing the engine over. This all becomes even more critical during the very cold winter temperatures!!! (This is absolutely crucial for your car, which has plain bearings that float on a cushion of oil under pressure!)

So how do you know how pumpable your oil really is???? Some folks depend on the first number in the oil viscosity rating, for example the 10W in 10W40. But, just using this is to symplistic...and doesn't tell the whole story. For example, do you know that 10W30 is way more pumpable than 10W40....yet they both begin with 10W, so what's the deal????

To find the real story, you need to search out the Product Data for any oil you are now running or thinking of running! You should look for some numbers there that are Viscosity @ 40 degrees C (the units used are cSt).

http://www.redlineoil.com/pdf/4.pdf


For example, from the data chart for my favorite oil Redline, we can see that a 10W40 get a cSt of 93, where a 10W30 gets 70. That is a very significant difference of 23! Ok, so you may imagine that 5W30 is way thinner when cold compared to 10W30, but if you look at the chart 5W30 gets a value of 62. What??? The difference between 5W30 and 10W30 is only 8....compared to a difference of 23 for 10W30 vs 10W40.

So, we see that 5W30 and 10W30 are closer to eachother in cold start viscosity, than 10W30 is to 10W40, even though they both start in 10W!!!

So, do some research and find out what the actual cold viscosity of your oil is, and compare it to other products and other weights of oils. (Note...if the manufacturer of your favorite oil doesn't publish these numbers, consider that maybe it is because they aren't really very proud of what they actually are!!!)

 

Another thing to look for. As you do comparisons, note that the synthetics have way lower cSt's at 40 degrees C than does a petroleum oil of the same nominal weight. This is just one of the many ways where the synthetics excell over pain old fashion petroleum oils!!!

http://www.maximausa.com/produ...roke/atvpremium4t.asp


http://www.maximausa.com/produ.../maxum4synthextra.asp


An example, compare Maxima (another of my favorite oils) petroleum ATV Premium 10W40, with their own synthetic Extra 10W40. Premium gets a value of 111.6 and Extra gets a value of only 82.2. That is a huge difference of around 30! You can see that the difference between a petroleum 10W40 and synthetic 10W40, is bigger than the difference between Redline 10W30 and 10W40 (difference of 23) that I used in the post above!

Also, note that Maxima Extra 15W50 has a value of 116.8. So, you can see that petroleum 10W40 has about the same cold start viscosity as a synthetic 15W50. Now that should really open your eyes!!!

 

so you are looking for a low cST 40 number then? this means better flow for a cold start?

 

cSt 40, is a good indication of relative viscosity comparisons between different oil, on a cold start.

cSt 100, is what is used to determine the "weight" of the oil. (The second number, 30, 40, 50, etc.). If an oil has a cSt of 9.3-12.5, it is called 30 weight. 12.5-16.3 is 40 weight, and 16.3-21.9 is 50 weight....etc., etc...

So, you can see that the "weight" of an oil actually represents a range of viscosities, and not just one partiuclar viscosity. A savy oil buyer, will check out cSt 100 as well as cSt 40!!!

For example, Maxima Extra gets a cSt 100 of 12.5, so it is right on the borderline between 40 and 30....so it is a "light" 40 (or a "heavy" 30, whichever way you want to call it). Maxima ATV Premium gets 14.92, so it is right in the middle of the 40 range.