Syn better at low temps?

[Matt89]

I've been trying to get my mind around something here.

Folks continually say "Synthetic is better at low temperatures"...but I question whether this really applies to the temperatures that we usually see.

Here goes my thinking:

Pennzoil 5w30, CCS is 5800 at -30C.
Amsoil 5w30, CCS is 5254 at -30C.

Given that -30C (-22F) is a temperature that most of us won't see, really how big of a difference is this?

In other words, if both the conventional and Syn oils are formulated to achieve a similar '5W' level of performance in the cold cranking simulator at ridiculously low temps, won't they show about the same resistance to pumping/cranking at more reasonable temperatures (say 0F and above)?

Would it not be possible for a 0W or 5W synthetic oil to be formulated such that in the usual operating range (0F and above) it was actually thicker at startup than a 5W conventional? In this case the syn oil would just offer less resistance to starting in the Extremely low temps where the conventional runs out of Schlitz.

I ask this question because I just can't tell that syn is so much easier to start in normal temps. I ran early '90s pennzoil 5w30 in Northern Michigan without the slightest problem.

 

[Ron AKA]

You are correct. There are some good low temperature conventional oils. See this other thread:

http://theoildrop.server101.com/forums/s...ge=0#Post733223

However, the good synthetics should be better still. Then the other variable to consider is 5w20 or 0w20 instead of 5w30. You will gain more from going to a 5w20 conventional or blend, than you will going from a 5w30 conventional to a synthetic. See this graph which shows the big advantage the 0w20's have for the more reasonable cooler temps.

 

[Matt89]

Good for me then, Motorcraft 5W-20 it is!

 

[Nebraskan]

Matt89, you might also read (lengthy) what AE Haas has to say about motor oils in general. At here: http://63.240.161.99/motoroil/index.html

You can also find this link elsewhere on this forum, lised by one of the administrators. He did extensive studies and put it into more common terms so we could undestand. Bottom line is that the lower you can get on the viscoisity index at the time you are starting your engine, the better off you will be. Synthetic has shown remarkable properties of not thinning down as much from 212 F operating temperature overnight as much as mineral based oils.

 

[Nickdfresh]

I'll still take a Group IV synthetic anytime in very cold snaps, if I have a newer car that is. And so does the U.S. Army, which has done significant cold weather testing of equipment in Alaska since at least WWII. And they currently recommend synthetic 0W-20 or 5W-20 in vehicles in extreme cold weather.

However, I agree Matt that you'll not notice a major difference in wear or performance conventional and synthetic. I doubt there is much of a difference between a quality conventional 5W-20 or 5w30 in cold weather start up either. In fact, I doubt there is a huge drop off in using most 10w30s in the cold (in an older engine) since I've done it many a times, and never had a starting issue during sunny and scenic January in Buffalo, NY.

In fact, I've used 20W-50 (Pennzoil) in single digit temps., and never noticed any significant problems with starting. I guess I'm trying to say that it is tough to base a lot on anecdotal empirical observations...

 

[Blue99]

Quote:

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Synthetic has shown remarkable properties of not thinning down as much from 212 F operating temperature overnight as much as mineral based oils.

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"Oil thins at hot temperatures and thickens as it cools."

Repeat the above statement, multiple times, until the concept sinks in.