yes you could have variations between manufacturers because the first number is rounded to the nearest 5 and the second to the nearest 10, but all things being equal, the 5W rating is going to mean its thicker right through to the upper temp viscosity.
No it won’t. For some the 0W will be thinner above -30 or so.
No I don't think so. The OEM's themselves say its 2-3% CAFE benefit. I have seen about 1.5 to 2% by my best calculations going from 0W-16 to 5W-30 in my Rav4. So in100K miles I will use an additional 69 gallons of gas. At todays prices what would be $30 a year or so for me.
There is no rounding error. 0W, 5W and 10W are specs, not numbers. In fact there identical specs - the only thing that changes is the temperature which they pass the two tests at. So a 10W passes the same test but at a warmer temperature than a 0W passes it. If you live where I do it makes very little difference to anything.
Here's an example (Valvoline Extended Protection) where a 0W-20 (KV100 = 8.4 cSt) is thicker at 100C than the 5W-20 (KV100 = 8.3 cSt).
The W grade rating is not "rounded". The oil is tested for both Cold Cranking and Pumpability per SAE J300, and whatever the lowest W grade it meets satisfying both the Cold Cranking and Pumpability specs gets assigned to the oil. The actual dynamic viscosity (cP units) at the required temperatures are tested in special equipment and determined to assign the lowest W grade the oil meets.
The data there does not disprove what I am saying and rather confirms it, though in the specs there is very little difference between those two oils, but that is only based on 3 data points, the most significant being -39 0W and -36 pour temp, 5W
It certainly does disprove your claim because you claimed a 5W is going to be "thicker right through to the upper temp viscosity."
Doesn't matter what the VI is, your claim is still false. A 0W-20 can be thicker at 100C and even lower temps than a 5W-20 … you claimed it couldn't be. Those spec sheet links I posted proves it can be.
If an oil remains at a higher viscosity through the temp range its thicker, just comparing one temp and saying the other is 1/10 of centistoke thicker at one temp at the end of the range does not mean its a thicker oil
of course there is rounding.......we dont see numbers/specs ending in anything other than 5s or 0s, do you really think manufacturers are able to produce an oil that is exactly 5w or 0w?
Yes, I wanted to say that same thing - two 0W may have different viscosity at certain negative temp. and we can see that by its higher CCS value/number.
It doesn't have to be higher through the whole temp range to make your claim false. Go back and read what your claim was. The 0W in post 85 was thicker at 100C than the 5W, and started being thicker at some point between 40C and 100C.
Look at the spec sheets in post 85, both are a KV100 20 grade. They have the same KV40 at 44 cSt, yet the 0W has a higher KV100 than the 5W. That means at some temp between 40C and 100C the 0W was thicker from that temp to 100C. That is the graph. So again your claim is false.
The measured viscosity falls into grade ranges as defined in SAE J300. There is no "rounding" of the viscosity involved - the viscosity is what the measurement finds it to be. Have you even seen J300?
???
Penrite also has a few 70s:
The MOFT changes dynamically on the rod bearings due to the dynamic combustion load on the rod based on throttle opening and the forces due to the mass inertia reversal when the piston and rod changes direction at TDC and BDC. That's why rod bearings wear more on the top bearing vs the bottom bearing because the MOFT runs lower on that side of the rod big end.
"That is the graph"
If you knew the typically shape of an oil's viscosity vs temperature curve on a linear axis graph then you'd understand that if two oils have the same KV40 (the oils in post 85), and the 0W has a higher KV100, then at some temperature before 100C the 0W oil's KV has to be higher from that point than the 5W in order to be higher at 100C. That's what the graph looks like. Go graph those two oils with Widman's plotting tool. Maybe I'll plot them for you tomorrow when I'm on my laptop with the plotting tool.
Totally agree with that. The post I quoted said the journal bearing constantly reverses, and that didn’t sound right to me.
Think he meant the reversal acton of the pistons and rods.
