SAE 40 oil

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Mar 13, 2003
North Front Range, CO
At Checker I see they sell SAE 30 SAE 40 oil. Why couldn't one use a SAE oil in summer?

M1 15w50 says it pumps at -39f and its pour point is -45. 5w30 pour point is -39.
Why wouldn't I use it in winter???
Typical Properties

Mobil 1 15W-50
SAE Grade 15W-50
Viscosity, ASTM D 445
cSt @ 40º C 125
cSt @ 100º C 17.4
Viscosity Index, ASTM D 2270 153
Sulfated Ash, wt%, ASTM D 874 1.3
HTHS Viscosity, mPa·s @ 150ºC ASTM D 4683 5.11
Pour Point, ºC, ASTM D 97 -45
Flash Point, ºC, ASTM D 92 230
Density @15º C kg/l, ASTM D 4052 0.864
I wounder if I went to a M1 15w50 I would still suck oil at high rpms like M1 0w40 and M1 10w30 does?
[quote author=landtoy80 link=board=2;threadid=6486;start=msg52500#msg52500 date=1066572222]
At Checker I see they sell SAE 30 SAE 40 oil. Why couldn't one use a SAE oil in summer?


Why? Is it cheaper than multi-grade? By enough to make it worth it?
Pour point does not tell you anything about the thickness of the oil at cold temperatures. All that pour point means is that they put some oil on a plate and after putting the plate vertical for 5 seconds they see some movement (thing really thick molasses). The more telling comparision is the Cold temperature pumping thickness. At -25c, Mobil 1 15w-50 will be about 9000 cst in thickness (questionably pumpable), while the 5w-30 at the same tempurature will be about 3000 cst. Another way of looking at it is the 5w-30 is the same thickness as the 15w-50 at 15-20 C lower tempuratures. If you don't ever encounter really low tempuratures (below about 10f) you could get away with the 15w-50, otherwise go the lighter oil in the winter.

In the summer, you could use a straight weight oil, but why? At operating tempurature a 15w-40 or 10w-40 will the same thickness as straight 40 weight. The multiweight will also give better startup lubercation. Also, most straight weight oils do not meet current standards (they tend to be cheap base stocks with poor addtives). Stick with multiweight, there is not benifit to the straight weight.

I went with the Chevron Supream dino10w30 for winter and will go with 15w40dino for summer. I have always used 10w30 in winter in WI and CO and it worked fine.
As I had good luck with Rotella 15w40 (no rapid oil use in high rpms) should I try Chevron or keep with Rotella next summer?
The Chevron is considered a little better, but the Rotella is also a good oil. Either of them will work fine. I would recommend that you use a 5w-30 oil in the winter instead of 10w-30 because the 5w will pump better and be thinner at the cold temps you see in the midwest.


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