Originally Posted By: Johnny
Hope FrankN4 sees this thread. He uses Mobil 1 15W-50 in everything he and his family has and uses it year round.
If it ain't broke, don't fix it.
I sent FrankN4 a PM so maybe he will jump in.
First. let me say that I have absolutely no brand loyalty. If I find something tomorrow that meets all of my requirements better than Mobil 1 15W-50, I will change tomorrow.
Mobil 1 15W-50 has a pour point of -39. That is the same as many 40 grade oils. 0W-20 through 10W-30 run pour points of -40 to around -45, basically, there are exceptions.
This past winter, we had 8 to10 days where the night time temperature dropped below 10F, but none below 0F. My Toyota, Cavalier, and Silverado all started literally before you could release the key. 0F definitely not to cold.
I have heard it said that a 0W-30 would pump/circulate faster than a 15W-50. Many years ago I was adjusting the valves on a motorcycle that had the nut and bolt adjusters. I pulled the plugs so it was easy to turn the engine and keep it where I wanted. I had my wife push the kick start to turn the engine. I noticed oil flowing in the heads just from the kick start pressure, and it flowed immediately. This was a 20W-60 conventional oil. I looked under the valve covers of some of my vehicles with a bore scope/light. I removed plug wires or distributor wire and cranked engine. Oil flowed immediately with just a tap on the starter. Because of this, I PERSONALLY, do not believe there is any appreciable oil flow advantages to a XW-20 or 30.
Mobil 1 15W-50 has a 40C cSt of 131.2. Rather low for a 50 grade. It has a 100C cSt of 18.1. Again, low for a 50 grade. The HTHS is only 4.5. Mobil 1 15W-50 is by no means a thick oil. Just look at the PDS for other 5w/15W/20W-50 oils. I run mostly low RPM engines and Mobil 1 15W-50 is easily thick enough to be pumped by the low peripheral velocity of my journals. It also has the viscosity reserve for the 230F oil temps across the Smoked Mountains with camper pack and trailer. If Mobil 1 15W-50 were just a little more viscous or just a little less viscous, had a lower HTHS, had a different add pack, I would not even consider its use.
I do not believe there is any measurable difference in gas mileage between a 5W-20 and a 15W-50. Just look at the API web site. Uneven tire pressure, running with open windows, air density, air temperature, the way you drive, where you drive, all will have more effect on fuel use than viscosity.
Mobil 1 15W-50 is SM rated and it has a ZDDP pack of 1200. Not overly high but more than sufficient for my uses. The calcium content is not so high to compete with the ZDDP but not so low to not effectively keep the engine clean.
I do not want to write a book here. I know of nothing better for my use in my geographic location. I would probably consider something different for winter use if I lived in Frostbite Falls.
I might should add that since 1990, I have 2,000,000 miles on M1 15W-50 with never an engine problem, no consumption at all, no leaks, no seeps, and always better than EPA estimates. I ran it in everything from DOHC SMPFI 1.5L I4 engines to big GM V8 engines.
If Amsoil, Mobil, Pennzoil, or Valvoline were to come out with a GPIII, GP III/IV blend, or a GP IV oil,(I PERSONALLY prefer the III/IV blend) 40C cSt of at least 80, 100C cSt of at least 13.5, SM level ZDDP with a moly reinforcement of about 300, absolutely shear stable over 3000-3500 miles, HTHS of at least 3.8, a heavy FM content, low(1 or less) SA, that might entice me to look seriously at a thin oil.