I run 10w-30 all year round. And yea that includes the car being in the garage 4/5 months of the year (WINTER) I still take the car out for a drive on a nice winter day though I also use maxlfe if it matters....

 

5w30 thins out faster and shears down. 10w30 is much more stable. Use 10w30 whenever you can. Plus most synthetic 10w30's will outflow a conventional 5w30.

 

Thinner oil also means it will flow better when cold=better protection. When you run into problems is when the oil gets too hot and breaks down causing metal to metal contact. If an oil is doing its job, metal parts should never rub. 5W-30 should be good for all year around unless it get down into the negative degrees area, then 0W-30 may be the way to go.

 

Where do you get this information? Do you work for some oil company or did cousing Billy Bob tell you that.

 

Which is a good reason to use the 0w40 I was talking about earlier. You get the cold start up flow of a 0 weight, and the warm protection of a 40 weight. The thicker the oil, the better the protection.

If you guys want to keep running 5w30 oil just because it says so on the oil cap that's cool with me Don't you think oils have changed since 93-97 when these cars were produced?

 

the mobil 1 RED CAP is 15w-50...that is way to heavy to run. I use that stuff in my dirtbike sometimes, sometimes even 20w-50. In my car i just use Castrol GTX 5w-30, the manual recommends 5w-30, but says 10w-30 can be used. I'm not sure what is recommended for the LT-1's, but i'm sure either 5w-30, or 10-30 will work fine.

 

Is the 0w40 suggested to use all year around or just for the winter time when its cold? Maybe i'll try this stuff next oil change.

 

I'm going to use it year round.

 

www.bobistheoilguy.com Many oil companies put out spec sheets on their oils. Ask Patman. You can learn more than you ever wanted to know about oil on that site. As for oil shearing down that's from reading various used oil analysis.

 

I use 10w30 but I am switching to 0w40. I would have already switched but the store only had 4 quarts left.

 

Even though a 10w30 synthetic will still flow well in the cold, a 5w30 will always flow better on a cold start, and yet again a 0w30 (or 0w40) will flow better than the 5w30.

I ran 10w30 last winter, but my wear numbers (in oil analysis) were not all that great. It got down to -10F a couple of times. I would not recommend using 10w30 if you're going to see a lot of temps below freezing.

To be honest, with a good synthetic oil, you could just use 5w30 or 0w30 all year round no problem. A well built 5w30 or 0w30 synthetic can maintain it's hot viscosity without thinning out too much. For instance, in my first interval with the German made Castrol 0w30 Syntec, it's viscosity at 100c stayed unchanged, my new oil sample tested out at 12.2 cst, and so did the used sample after 3100 miles. And because this oil is a very thick 30wt (almost a 40wt, since 40wt begins at 12.5cst) it will protect in the extreme heat very well.

In terms of cold weather performance, Amsoil's 5w30 and 0w30, Redline 5w30 or the German Castrol 0w30, are some of your best choices.

 

well the temp in nyc during the winter can get down to single digits on some days. so i will use either 5w-30 or 0w-30. Now what do u think of Mobil synthetic 5w-30. I've also seen the German made castrol at the local Autozone.

 

I'm still not a big fan of Mobil 1 5w30, I haven't seen it performing all that well in GM V8s in the oil analysis reports I've seen. LT1s and LS1s like an oil that is a bit thicker, something on the high end of the 30wt range, where Mobil 1 is more on the low end. Recent M1 5w30 reports have shown it to be a little bit thicker than before though, so it appears they may be reformulating it in the right direction. So if anyone here is running M1 5w30 in their LT1, I'd love it if you'd get an oil analysis done to see how the wear numbers look. I've got 40 bottles of the GC 0w30 right now though, so I won't be switching brands anytime soon.