Thing is at least for my Caprice 10w30 is fine as long as it stays above zero(or maybe 30) according to the manual, some of the 5w30s run very thin like Patman said M1 5w30 is almost a 5w20, Amsoil on the otherhand comes in at almost a 40wt. Now if some oils are known to run thin and a thicker oil(be that brand or weight) like a 10w30 is OK as far as the manual goes then warranty is safe why run the 5w30. On the CAFE thing, yes little cars help that but so does squeezing any extra milage they can from the rest of the line.

 

what do you guys think of the royal purple stuff?? or if thats what its called.

 

lol goddamn, quit arguing and please someone answer my damn question...

Thanks.

 

Well, here's the best answer you've had all day! LOL.

 

OK, here is my list of some of the oils I recommend for the LT1:

German Castrol Syntec 0w30
Amsoil 5w30 or 0w30
Redline 5w30
Royal Purple Racing 41
M1 0w40

(there are more of course, that's just a quick list)

 

What the hell good are all these societies and groups if all these oils say a certain weight on the bottle, but are actually a different weight, viscosity, etc.? Seems to me there are standards, I think its BS if you buy say 5W30 when actually its more like 5W40 or 10W30, etc? WTF is going on?

 

It's not BS. For example, if an oil is going to qualify as a 0w30, 5w30 or 10w30, it's gotta have a viscosity of between 9.3 and 12.5 cst at 100c (212F). That is the allowable range. So you can have one company that prefers to make their oil on the thin end of that range, and another one that prefers to make it on the thick end.

So when I say that the German Castrol 0w30 is a lot like a 0w40, it's because it's viscosity starts out at 12.2 cst, so it's only a tiny bit away from being a 40wt. And in my last oil analysis it did indeed thicken up to 12.9, so it turned into a 40wt. (nothing wrong with that behavior at all, it's more desirable than an oil which thins out in fact, and it's viscosity change from 12.2 to 12.9 is only a 6% change, very reasonable)

 

On the RP question, from my reading it sounds like the racing version is the only one worth bothering with the street stuff sheers down to a lower weight fast.

Patman and our Impala board oil guru both gave me their blessing on my oil choice but till I have it tested I am a guineapig.

 

Do most part stores carry german castrol 0-30? Is there anything different about the bottle than the normal stuff, I'm about due for another oil change...

 

Autozone is the only one I'm aware of that is carrying the Castrol German oil. Read the back label to be sure it says "Made In Germany".

 

i'm running Redline 10W-30 in a 94Z

but it never gets hotter than 90 F here or colder than 65F

Redline brags that the 10W-30 has a hot operating viscosity of a 40W so i guess i'm ok