xviper

Thanks guys, I've learned a great deal on this thread. Never knew oil could be so complicated.

naishou

The statement that the "W" ratings are measured at 0*F is wrong. See the table in the link I posted. The temperature depends on the SAE grade but is far lower than 0*F for almost all of them. 10W is measured at -31*F for example.

StwoK

This is your quote.
This is actually the quote from the article.
The W (like in 5W-30) stands for the Winter rating, some people say weight.

Read the article. there is some interesting information there.

naishou

[QUOTE]Originally posted by StwoK
[B]This is your quote.

StwoK

The point I'm trying to make here, is about protecting the moving parts in your engine when the temperature drops. At -20 F most petroleum based oil are becoming very thick and in this state the oil does not protect metal parts from wear when the engine is started. Synthetic oils are superior in the cold and will pour freely far beyond any petroleum based automotive oil. The fact that they are still in a liquid state means they can protect those moving parts at start-up time. Once again the problem with petroleum oil are the things which cannot be refined out of the oil. One of those things is paraffin (wax) which in cold temperatures start to congeal. Just before the oil becomes solid, its consistency is similar to jello. It is at this point that the lowest pumping viscosity can be found! Oil cannot protect an engine in this state. And I will say this again, there is a difference between 5w-xx petro based and 5w-xx synthetic.

I have copied a few things again from 2 oil websites.
-----------------------------------------------------------------------------------

The first is from Exxon's Tiger Tips !

"Will a synthetic oil really make my winter driving easier?"
Not just easier, it can make winter driving possible on days when many vehicles simply won't start. Synthetic oils, such as Superflo Synthetic, contain none of the wax you find in non-synthetic oils. In cold weather, crystallized wax often makes an oil so stiff that the engine can't turn over and start. But wax-free Superflo Synthetic stays fluid at -50

naishou

The mystery is solved! What it comes down to is that most synthetic oils will exceed the pumping viscosity spec for their SAE number easily but meet the cranking viscosity spec (at 5*C more than the pumping spec temp) in the same way as mineral oils. If this were not the case they would have a lower SAE number.

Really, that's very interesting and probably useful to people in a really really cold climate but if you're using 5W oil for example, there is no difference until beyond -25*C (-13*F). The conventional oils get a lot thicker in the next -5*C and the synthetics do not. Now there is nowhere on the entire continent on which I live where it has ever reached -25*C, so this is completely irrelevant to me and most others. If you live in northern Canada or Siberia, then great.

There are of course other benefits of synthetics including evaporation and film strength, but the viscosity thing is a bit of a red herring for most of us. Just trying to clarify the facts here.

xviper

[QUOTE]Originally posted by naishou
[B]Now there is nowhere on the entire continent on which I live where it has ever reached -25*C, so this is completely irrelevant to me and most others.

StwoK

naishou ..... I live in north west Ohio and we haven't had a hard winter for about 12 years. There was one year in the early 80s we had a week of high winds out of the west in January. The air temperture was about -20 F everyday (colder at night) and with the strong winds, the wind chill factor ran in the mid -50 F that week. Where I work, the first row of the parking lot faces west into the wind, everyday there were cars that would not start or their raditors frooze and ruptured. The cars facing east had fewer problems! I was driving a Datsun 280Z at the time. The engine had Moibil 1 10w-30 and the anti-freeze was set to -36 F. Never had a problem. Some of my friends were so impressed they started using Mobil 1 too. The funny part is, I work for an oil company and it's not Mobil. Where's my company loyalty

jguerdat

[QUOTE]Originally posted by naishou
[B]The mystery is solved!

mike2k

Well yes, I did last year, found it too thick for my S2K !! changed to 10W30 (all Synthetics) - engine rev better! Now using 5W30. I do not know why Honda recomended the 5W40, it is too thick at operating temperatures and cold ambient air. Just my experience...

Mike