i was researching at the BOBis the oil guy site and was told that our engines fond of using 10w40. do any of you guys run that in your lt1's? also does anyone know if its safe to run 6 quarts or is 5.5 the max?

 

I wouldn't push it beyond 5.5 quarts.

It was me who suggested that the LT1 might like 10w40 better, since it's clearances are bigger than most new engines, and most of the LT1 oil analysis results I've seen on the thinner 30wt oils don't show all that great wear numbers. I'm going to be trying out an oil that's on the very high side of the 30wt scale next, so it's almost a 40wt. If I'm still not happy with the results I'll probably step up to 10w40 Amsoil next year sometime.

 

thanks for the help yesterday, just wanted to see if other people were doing the same thing

 

I'm interested too. Most people here probably use 5w30 since GM puts in the owner's manual not to use 10w40, but I don't see a problem. Some of the older 10w40 dino oils used to contain a lot of polymers, so they'd thin out quickly and cause more sludge in the engines. But nowadays the oils are a lot better, so even a dino 10w40 won't cause a problem, as long as you change it every 3k or less. A good synthetic 10w40 like Amsoil or Redline should stay pretty close to it's original viscosity too, it won't thin out and cause sludge at all, so there is no harm in running an oil like this. You'll lose a tiny bit of power and a bit of MPG, but not a significant amount, and my strong hunch tells me you'll get longer engine life. Most of the 5w30s and 10w30s available out there are very thin, almost 20wt oils, and with the larger clearances in the LT1 engine, that thin oil won't protect as well.

Don't forget, underneath it all, the LT1 is not too far off from a good old small block Chevy. Many people used to run 10w40 in these engines with good results.

 

I run 10W40 in my 383 because thats what he suggested. He also thinks its better to run 10W30 than 5W30 in the LT1.

 

I have always ran 10w30 in mine with no problems whatsoever. I also run it in my daily driver, and when i change the oil in my mom's car. If you live somehwere liek here in AZ, I would recomend a heavier oil with this heat...

 

Good question. My thinking is that since a new lt1 probably doesn't break in fully for several thousand miles that maybe the clearances aren't as loose as believed.

I use 5W30 synthetic. That's what the factory put in it (SLP) and that's the wt recommended in the new vettes (LS1 w/ al blocks.

I figure that if your engine is tight to begin with and you use a light syn oil like 5W30 that your engine will stay tight longer.

Now this may equate to not getting the extra power that may go with break in, but the way I see it once you get to "break-in" you are now on the way to past break in and on your way to "break down" (wear).

So in conclusion I believe that using 5w30 or even 10W30 synthetic should provide good flow and protection without premature wear.

On the other hand my engine spun a bearing about the time it should have been broken in (8000 mi)
Go figure.

 

Nerd Alert

 

Lounge time.