Additives vs. viscosity for cold starts

[addyguy]

Usually, when you drive in a cold climate, you use low-viscosity oils to aid start up during cold weather.

But if you added a really slippery oil additive to a thicker oil, would it make start up just as easy?

Normally in a 'northern' winter, you would use a 5W or 0W oil to make start-ups easy at, say, -18C to -30C at the extreme end.

10W-30 would 'work' most would agree, but it wouldn't be ideal, and most OM's say not to use it below -18C.

Moly is generally regarded as a very good additive at reducing friction in an engine, making it run much smoother and even get better mileage, as it 'plates' on the surface and reduces friction a lot.

If you added a moly additive, like MolySlip or Liqui-moly to a 10W-30 oil and ran that through a winter, would it make the engine easy to start even if you were at temp close to where a 10W oil would have a hard time, ie -25C? Would the engine crank faster bc the plated moly wold reduce friction enough to compensate for the thicker oil?

 

[SuperSalad]

The purpose of the low viscosity in the oil is for oil delivery by the pump, not for friction. I think you are confusing two very different things here.

Internal friction of the oil is part of the viscosity, but friction reducing additives do not work on internal friction, they work on the surfaces.

 

[Hammehead]

It would increase protection at dry starts and may lower friction at dry cold startup, if, as a solid lube that supposedly stay in contact with metal surfaces, even after oil drainage.

 

[rideahorse]

If you are worried about dry starts don't use a syn thin oil. We run 15w-40 in every thing thru the winter. Even in -15 F weather with no problems. The drain off of thin syn oils is far worse than dino oils.

 

[andyd]

A BIL of mine was in Burlington VT. Tried to start his Cutlass. probably had 10w30 at 30 below. Spun a bearing. I would only go down to 5wxx. Then use a block heater.

 

[RamFan]

Originally Posted by rideahorse
If you are worried about dry starts don't use a syn thin oil. We run 15w-40 in every thing thru the winter. Even in -15 F weather with no problems. The drain off of thin syn oils is far worse than dino oils.


Ok buddy.

 

[Pelican]

Originally Posted by addyguy
Usually, when you drive in a cold climate, you use low-viscosity oils to aid start up during cold weather.

But if you added a really slippery oil additive to a thicker oil, would it make start up just as easy?

Normally in a 'northern' winter, you would use a 5W or 0W oil to make start-ups easy at, say, -18C to -30C at the extreme end.

10W-30 would 'work' most would agree, but it wouldn't be ideal, and most OM's say not to use it below -18C.

Moly is generally regarded as a very good additive at reducing friction in an engine, making it run much smoother and even get better mileage, as it 'plates' on the surface and reduces friction a lot.

If you added a moly additive, like MolySlip or Liqui-moly to a 10W-30 oil and ran that through a winter, would it make the engine easy to start even if you were at temp close to where a 10W oil would have a hard time, ie -25C? Would the engine crank faster bc the plated moly wold reduce friction enough to compensate for the thicker oil?


40 years ago 10W30 was also a winter oil, but at least 50% of cars then had block heaters for when the temp really dipped, also we used to let the car idle for a few minutes before driving off. When lower viscosity oil became available block heaters lost popularity and hardly anyone today idles the car to reach good pumpability.

 

[Ducked]

No.

Still need to pump "thick" oil.

How could adding solids make it "thinner"?

 

[Garak]

Yes, that's the real problem. Addyguy does bring up a point, though, and that was something that was trumpeted by snake oil salesmen for years, claims that their product could get around the poor pumpability of whatever might be in one's sump, by reducing friction and protecting the engine before the oil can actually do anything. Now, that may, indeed, be still part of their marketing, but I pretty much have ignored additive marketing claims for many years.

 

[Shannow]

Engines don't start "dry"...they do when we build them, so we use assembly lubes, but after they've run, there is a lot of oil in bearings, in piston skirts and rings, between cams and followers. Pull apart an engine and you will find it there, and you will get filthy.

As I said, build them, and use assembly lubes, adding wear reducing "additives" to the surfaces so that wear is minimised until started.

This thick, cold oil that's between all these surfaces places a drag on the starte, that's purely hydrodynamic in nature (potentially with a shear stress if gels have formed).

That's why the "CCS" (Cold Cranking Simulator) test is a part of the test regime for oil specifications. It's the ability for the starter motor to spin the engine to the point that it will likely fire.

It's viscometrics, on the oil remnant after last run, and held in place by Capillary action. Surface active coatings and friction reducing solids don't affect that.

MRV is the ability for oil to move to the pickup after pumping starts...if the MRV is hopelessly inadequate for the temperature, maybe additives will help reduce wear, but the Myagi defence should apply here..."best defence is no be there"...it's no substitute for the proper oil.

 

[Patman]

Originally Posted by rideahorse
If you are worried about dry starts don't use a syn thin oil. We run 15w-40 in every thing thru the winter. Even in -15 F weather with no problems. The drain off of thin syn oils is far worse than dino oils.


Complete nonsense. As Shannow said, engines are never "dry", all oil (synthetic or conventional) will stick to the parts for a very long time after shutdown. Want proof? Go to a junkyard and tear down an old engine that's been sitting there for a long time, it won't have any dry components inside there at all.

 

[demarpaint]

Originally Posted by RamFan
Originally Posted by rideahorse
If you are worried about dry starts don't use a syn thin oil. We run 15w-40 in every thing thru the winter. Even in -15 F weather with no problems. The drain off of thin syn oils is far worse than dino oils.


Ok buddy.

Lol

 

[ofelas]

I'll add that on a tractor engine/genset that's seasonal, I see more oil clinging to valve train parts when that engine's been run on syn oil.