Mobil 1 oil weight

[cody at 5000tq.com]

Quoting Ameer Antar <antar at comcast.net>:

> I agree that 0w40 is too extreme for my old car, but I was
thinking 
> of sticking
> with 10w30. I based this off the fact that the S6 has a similar
engine design
> and has a similar oil grade chart to mine. So if A=B and B=C,
then 
> A=C, right?
> Keep in mind this is a rebuilt motor, so it's not like I'm running
on 22+ yr
> old bearings.
>
> -Ameer

And this is the grey area that I have issues with too. I've been
trying to figure out the best oil for my car since I rebuilt the
engine a year ago. After the break in I went to 10w30 Mobil 1 with no
issues, but then switched to 5w40 Castrol Syntec. The 5w40 Syntec
meets VW 502 and 505 and is highly recomended for use with turbo's.
Buuuut I do worry that it's too thin, remember that I am talking
about 8,000rpm and over 500hp on my 5ktq. So does it matter more that
it's got all of the special chemicals to give the turbo constant
sexual pleasure, or should I be more worried about a $25 set of rod
bearings? It's a hard call.

I absolutely believe that the engines with thier factory set of
bearings, and especially those at factory performance levels, should
be running factory specified oil - 15w40 is my choice in the case of
a 5kt engine. But where does the line get drawn to decide when
performance needs have mandated an oil grade change? The line is
waaay too blury for any person, Bob the (self proclaimed) oil god or
otherwise, to dictate what anybody else should do.

Heres some other food for thought. I talked to my brother-in-law, a
former member of Champion Racing, today about this subject. He
informed me that in the S4's and the RS6's they were supposed to be
running the German Castrol (for corporate reasons). After pouring the
castrol in the engine in plain view they would later hide themselves,
drain the un-used Castrol out, and put in Mobil 1 5w30. He said the
engines made all kinds of noise with the Castrol, which the M1
instantly fixed. The weight was recomended by Cosworth Technologies,
who built the engines. Now the relevance here is sketchy - we are
talking about custom race engines built with definately modern
tolerances and parts, but at the same time we are also showing the
durability of the Mobil 1 on the lighter end of the spectrum.

Check out this blurb from Mobil 1 website:
"Why are you reintroducing Mobil 1 15W-50? Have there been any changes
to the formulation, or is it identical to the previous product?   

Mobil 1 15W-50 is being reintroduced based on popular demand. Mobil 1
15W-50 provides higher viscosity, designed to provide extra protection
for performance vehicles and vehicles that operate in severe service,
such as towing, hauling and racing. Additionally, Mobil 1 15W-50
contains higher levels of anti-wear (ZDDP or Zinc
DialkylDithioPhosphate) that may be required for certain racing
applications and camshaft designs. This is a new Mobil 1 15W-50
formulation and is not the same as the product that was marketed a
few years ago. "

Final thought - my 5k no-t is going to continue to get whatever is
handy, usually Castrol GTX 20w50 or Kendall 15w40. My fast 5ktq is up  
in the air
between 5w40 Castrol Syntec and something like 10w30 Mobil 1 or even
the 15w50 M1. My stock 5ktq will run the 15w40 Kendall, only because I  
don't want to start leaks by going to synthetic.

-Cody Forbes
http://www.5000tq.com