Does ht/hs and VI's matter in cold climates?

[byez]

1)How likely is an oil to reach temperatures in which they will shear in climates such as northern Alberta during the winter? Or does shearing occur regardless of ambient temperatures?

2)Is shearing less likely to occur with PAO synthetics? Or is shearing only an issue with conventional oils?

3)Are thicker oils of lower viscosity index more resistant to fuel dilution? If not, what is an indicator that an oil will stay robust within the presence of fuel?

4)For delivery vehicles, with oil constantly being heated and cooled. Would a 0W30 synthetic or 10W30 synthetic protect better? Start up wear vs. oil wear?

 

[StevieC]

The Thermostat keeps the engine at the proper temperature so heat is still and issue in the winter. Now it's less of a concern in the winter because the oil in the sump has a chance to cool because it is surrounded by frigid air but it is still in contact with hot metal parts so it will see some shearing but a lot less than an engine in the summer time in Texas for example.

Shearing happens with all oils... It depends on the oils composition and additive package. Syns are better than dino and some syns are way better than other syns... Check out their HTHS values. A higher number is best if this is what you are concerned about.

As for a delivery vehicle that is being started and stopped multiple times per day I would go with the 0w30. You want the oil to flow as fast as possible on start up to minimize wear and because the oil is going to cool somewhat between trips in frigid weather.

In the summer you could run a 10w30 if it is cheaper or you wanted to but I would use the 0w30 year round.

Fuel dilution is a non-issue today in mechanically sound engines that have been maintained. Computer fuel control is making this problem virtually non-existant in today's engines so I wouldn't worry about it unless you have a "Direct Injected" engine in which case the technology hasn't been perfected yet. Most cars on the road today don't have this D.I. technology. (Thank God) or the engine is worn out, fuel injector problems or the engine has been poorly maintained.

 

[BuickGN]

I think people put way too much weight on startup oil flow. As long as it's the correct viscosity for the temperature, there really isn't a measurable difference in time to full pressure and flow. In a Canadian climate I would want a quality 0w or 5w. With a high quality oil there's little to no downside to the 0w or 5w. The word here is quality. I would not run a conventional 5w-40 but I would have no problem with a synthetic 5w-40.

 

[BobFout]

Originally Posted By: BuickGN
I think people put way too much weight on startup oil flow. As long as it's the correct viscosity for the temperature, there really isn't a measurable difference in time to full pressure and flow. In a Canadian climate I would want a quality 0w or 5w. With a high quality oil there's little to no downside to the 0w or 5w. The word here is quality. I would not run a conventional 5w-40 but I would have no problem with a synthetic 5w-40.


That's the great thing about 5w40, I don't think there is a conventional 5w40 (I've never found one in stores or online yet in the past 6 years), it's synthetic only. Same for 0w40.

 

[crinkles]

where we come from, we shear ours!

 

[mechtech2]

Shearing is physically breaking the oil molecules in to smaller ones.
Temperature is not the main contributor.

But at lower ambient temps [Canadian Winter], the oil will not get to the same running temp as when it is summer.
This will keep your HTHS up , in real life.