Popular Mechanics - light grade oils

[CELICA_XX]

I was reading in Popular Mechanics about the current trend towards 5W-30 and 0W-20 viscosities by various manufactures over the last decade or so.

Most of it is common knowledge... they explain how most wear occurs when you first turn the key, no matter how hot or cold the weather is.

They also explain how many people don't really understand oil classification. A lighter grade oil is not a "thin" oil, it just acts and flows quickly under low temperatures.

At -15 degrees, for instance, 5W-30 takes 10 seconds to reach the rocker arms, compared to 20 seconds with 10W-30. But the interesting thing is that 5W-30 is flowing freely to the rockers in 40 seconds, whereas with 10W-30 it takes 3 minutes! Plus it provides the same high-temperature protection as 10W-30.




Even with older cars that recommend 10W-30, since the lighter oil will definitely travel to moving parts faster, wouldn't a lighter grade oil (like 0W-30) always be a better choice?

 

[brandini]

Usually yes, unless your motor destroys oil. Oils with less of a range are generally more stable so a 20W-50 is a rock compared to a 0W-40.

 

[Steve S]

What about if the temps are 60*f?

 

[CELICA_XX]

Originally Posted By: brandini
Oils with less of a range are generally more stable so a 20W-50 is a rock compared to a 0W-40.


Could you expound on this for me?

 

[CELICA_XX]

Originally Posted By: Steve S
What about if the temps are 60*f?


From what I understand, as the ambient temperature rises... 0W-30 and 10W-30 become more and more similar.

Correct ?

 

[HTSS_TR]

If 5W30 is so much better than 10W30 in cold start and it provides the same high-temperature protection as 10W-30, then why Honda recommends only 10W30 for S2000 until model year 2005 ? starting model year 2005 Honda recommends 10W30 in warmer climate and 4W40 in colder climate. The reason behind the recommendation of 10W30 for S2000 is it's more shear stable than 5W30.

 

[Spyder7]

Originally Posted By: HTSS_TR
If 5W30 is so much better than 10W30 in cold start and it provides the same high-temperature protection as 10W-30, then why Honda recommends only 10W30 for S2000 until model year 2005 ? starting model year 2005 Honda recommends 10W30 in warmer climate and 4W40 in colder climate. The reason behind the recommendation of 10W30 for S2000 is it's more shear stable than 5W30.


I don`t think there`s much, if any, difference between today`s 5W30 and 10W30 when it comes to the oil thinning (or shearing) over time. I`d even extend that to the newer 0W30 oils.

I don`t understand the logic behind a 10W30 oil in a warmer climate and a 5W40 in a colder climate. The winter grade makes sense, but not the viscosity. If anything I`d think the viscosity should be the other way around: 5W30 in a colder climate, 10W40 in a warmer climate.

I personally stick to 5W30 year round, since it never gets cold enough here to need a 0W oil, nor warm enough to bother switching to a 10W oil. And where the manufacturer specs only oil with a 30 viscosity rating, I stick to their recommendation.

Edit: even though the manufacturer specs only two oils (5W30 recommended, 10W optional in warmer climates), I`d have no reservation about moving to a 0W30 oil. In fact, as per the OP`s line of thinking in his last sentence, I can see the logic in it.

-Spyder

 

[Quattro Pete]

Originally Posted By: brandini
Oils with less of a range are generally more stable so a 20W-50 is a rock compared to a 0W-40.

Generally, yes, assuming both are made of similar base stocks. But if that 20w-50 is mineral and that 0w-40 is synthetic (I don't know of any 0w-40 that aren't synthetic), then I would expect the latter to be more stable over the course of an extended OCI.

 

[BobFout]

 

[BBDartCA]

Originally Posted By: BobFout

Thats misleading marketing bull.

 

[Jim Allen]

Originally Posted By: BBDartCA
[
Thats misleading marketing bull.


Maybe. Maybe not. These are not the only such statistics out there and if you were to do a freezer test of the range/types of oils they list, you would see a similar range of flow demonstrated. I have experienced such long delays personally and at the risk of shattering my current crackerjack reputation, I can attest that it took several minutes to get 20W50 oil up to the rockers in my Land Rover one decades ago Vermont winter morning. They literally were squeaking and you could hear them gradually stop as the oil finally flowed down the rocker shaft. That was one of my wake-up moments on oil viscosity and a lesson a California boy had to learn moving when moving into the north country.

 

[Steve S]

That is why there are those temp /viscosity choice charts in the manuals that give you a choice.

 

[Tempest]

The lowest recommendation I have seen for 10W30 is 0F. -15 is cold and one should be using the appropriate cold weather oil.

 

[Spyder7]

Originally Posted By: BBDartCA
]

Thats misleading marketing bull.


Based on ?

 

[XLR8R]

All else being equal, viscosity has a negligible effect on film strength?

 

[Ken2]

Originally Posted By: XLR8R
All else being equal, viscosity has a negligible effect on film strength?

The other way round. All else equal, film strength varies with viscosity. Of course, the load per unit area, pounds per square inch, of the bearing surface makes all the difference. Lighter oil on bigger bearings will carry more load than heavier oil on smaller bearings. The very big diesel engines running at 7500 hp per cylinder use 30 wt crankcase oil. How do the bearings handle that load?...adequate bearing surface area. The same principles apply with auto engines.

 

[Rob Taggs]

Wish some of this logic would sink in with two of my coworkers. Sub zero weather and they both start up their dumptrucks by first starting their trucks and not waiting for oil pressure to rise and then ramming the throttle like mad men. I just waiting for one or both to bust an oil pump by ramming the throttles with 15w-40 in those temperatures.