Why would you use 20W-50 in your engine even in elevated air temperatures - thicker is not always better.
The secret to good lubrication and cooling is oil flow, not viscosity. If oil thickness ( xxW-50) was the secret recipe for hot climates, why wouldn't you put in strait W-50 oil?
The oil flow to the bearings is (generally) dictated by the coolant temperature - lowering the coolant is possibly the best thing you can do for your oil.
In the old days, if you had 10 psi per 1000 rpm @ hot running temperture (never mind the viscosity), you were good to go....

Modern oils are pretty good, I had a rotax 2 stoke in my plane that needed 50:1 mix. Turns out on one occasion it had about 500:1, we flew for about 3 hrs duration no indications whatsoever.
Dont loose any sleep over a 0w or 10w

Fairly simple chart but you get the point. -20 F in Cali? Unless you're up in the highest mountain?

http://s1.hubimg.com/u/223700_f520.jpg

[QUOTE=Jager;290631]I live 15 minutes from Pismo, Harry's is a fun bar and it's close to the beach. :cheers:

Harrys...eh...scummy at times... Mr. Ricks is nearby in Avila Beach and always a nice bar for a good time. The Boardroom is right off the beach, left of the pier (if facing it from the parking lot), they only serve beer, but its a ********************in' place...good snacks too.

Yeah, anyone who makes claims like that (neighbor) is so full of it.

Oil viscosity is based on temperature, so the only extreme the engine would see would be way below freezing or "racing." Most synthetics in the normal viscosity ranges are more than enough to protect in street driving, esp CA.

more viscosity info
 

To go with ekam's chart, here's SAE J300 specs on viscosity grades. I've also provided the SAE J306 specs (gear oil) if anyone wants it.

Regards,
paul...

Just saw this, thanks & beware of Speed yellow boxster embracing it's freedom on hwy1 this Memorial Day! :eek:

I am not an oil expert but my understanding (which could be wrong) is that at high temps lower viscosity oils can thin and/or become aerated to an extent that will reduce the oil's ability to adequately lubricate the moving parts. Thus, it has been common practice to use higher viscosity oil in warmer climates in an attempt to mitigate these concerns.

And yes, some racers back in the day have been known to use single viscosity 40 or 50 weight but these days almost everyone simply runs a temperature appropriate multi-grade oil.

Last, its almost impossible to separate facts from marketing hype these days. Even if a straight 30 weight would work fine for many people (like it did for many of us, our parents, or our grandparents), the oil companies have marketed multi-viscosity oils so heavily that single viscosity oils are nearly obsolete regardless of the reasons/benefits/concerns.