ashzero

seems like mine is doing that. i thought it would get rid of it.

how does it compare to Amsoil?

i'm gonna try mobil 1 5w30 again on my next oil change.

tirefryer

Yes. Mine slapped much more with GC 0W30. I just switched to Amsoil 5W40 and the cold slap is almost gone. It is barely even noticable. It still does it on warm restarts but much less than the GC. Plus the Amsoil 5W40 has a 4.2 HTHS, which is higher than the GC. The higher HTHS will protect better when you are beating on her. Go with the Amsoil either the 5W40 as I did or the 10W40.

ashzero

is amsiol synthetic? can i find it at autozone? i dont remember seeing it there, but i'll check next time i go.

GuitsBoy

iTrader: (4)

I too noticed more slap with GC, but im willing to deal with it for the added protection. Between the true duals, the cam, the sewing machine valvetrain noise, etc... My car is loud on startup anyway. I usually warm it up a minute or two before driving it and the slap is gone by then.

tirefryer

Amsoil is synthetic. You can not buy it at Autozone. Go to www.amsoil.com to purchase. There are a couple dealers on this site that will give a better price. Send a message to them and see what kind of deal they give. Even if you purchase at full price it is not much more than the GC.

Rescue Ranger

iTrader: (10)

Patman, could you chime in on this? I'm curious..

Hardtop

iTrader: (3)

No, I think my valve train got quieter with GC.

Bruce

GuitsBoy

iTrader: (4)

I could maybe see my valvetrain having quieted down, but not the cold piston slap. Mine got way louder.

Rescue Ranger

iTrader: (10)

Now I can't decide if I should continue Redline 5w30 or try the 5w40 Amsoil for reduced slap... though is reduced slap sound really helping anything?

FstBlkz28

iTrader: (13)

When I first switched to GC 0w30 i noticed my engine got alil louder as well. However, it fixed my oil consumption problem so I'll deal w/ the extra noise. Besides.... now w/ the cam you can't hear it anyways

Patman

No piston slap in mine with GC. I don't think that changing oils can really cause more or less slap, since it's more of a mechanical issue. Going to a very thick oil might reduce the sound, but more because the thicker oil is more of a sound barrier than anything else. But you'd need to go to a 20w50 to see a signifcant reduction in sound, and that oil is simply too thick.

In some cases, a faulty oil filter can cause more engine noise on startup, which can be mistaken for piston slap.

01TA

iTrader: (7)

I also thought thicker oil would quite it down but is dosen't. I went for 5-30 to 10-30 M1 it got louder. Then went to 0-40 and it got louder again, all w/K&N filters.

eb02z06

iTrader: (18)

I noticed more oil councumption and more valvetrain noise with the Castrol 0W30. I talked to Patman and he suggested using a european 5W40 fromula.

BJM

iTrader: (1)

While it is a mechanical issue, oil is also a part of the running engine so it plays a role. I too tried the GC 0W30. The slap was much worse. Switching to regular Pennzoil 10W30 made the motor much quieter. Thinking about the engine and the role oil has tells me the following.

The LS1 has centred piston pins (no offset)
It has short skirt pistons
It has a very high ring pack

All of the above make the LS1 more sensitive to piston slap (than a SBC for instance) unless you are very careful with piston to bore clearance. GM simply missed the mark, their manufacturing tolerance scatter is wider than what the engine needs to make them all quiet. Patman it sounds like yours is within spec and oil type won't affect yours much (for slap that is).

To my mind the most significant improvement the oil can make to slap is to be thicker when cold, this will cause more drag in the con-rod bearings and cause the con rod to press the piston into the cylinder wall more firmly. If the engine oil thins out appropriately by the time the engine is warm, slap is reduced. The problem with a synthetic is that because the definition of a 0 weight and a 30 weight oil is so wide many formulations fit the definition. So a synthetic can be much thinner than a conventional oil at start up and the slap is much worse. At the 40 and 100 Celsius temperatures where the viscosity ratings are done the synthetic and dino oils are pretty close so they are given the same rating. This is why a room temperature synthetic can pour like water compared to a dino oil, yet they both might be 10W30.

I have heard lots of claims about Amsoil being good for slap motors. Not being able to find viscosity ratings at 0-10 Celsius means I will simply have to try it. My motor sounds like crap with the GC 0W30 although I am sure its a fine oil for a motor that was manufactured correctly.

Patman

The thing is here though, even though Castrol 0w30 is rated to flow much better in extreme cold, it's actually not thinner on most average startups. If you look at it's viscosity at 40c, it's actually thicker than most 5w30 and 10w30 oils! It's only once you get into the extreme cold where this oil isn't as thick. So it's thicker at both 40c and 100c than most 5w30 and 10w30 oils out there.

So it doesn't make sense that 0w30 Castrol would cause more piston slap if it's really a little bit thicker on startup (under normal weather conditions that is)

GuitsBoy

iTrader: (4)

Well, maybe the reason is because its thick. Five times already ive switched back and fourth between GC and M1 5w30, and every time the M1 is quieter during startup, particularly in the cold months. Perhaps its not piston slap but the lifters, and maybe the thinner oils help the lifters pump up earlier?

BJM

iTrader: (1)

Starting up in the summer, you're right it doesn't make much difference. Starting up this morning its only 3C. It makes a huge difference. +40C oil temperature is not my normal start temperature. What I have not been able to find is how much these oils diverge below 40C. I suspect they are all over the map. For what I am looking for I don't think minimum pour point is terribly useful either, its too far below what I need. The Royal Purple I tried had the best cold pour temperature of the oils I tried yet its worked best when cold which is the opposite of what I expected since it implies its thin when cold.

I just tried some Pennzoil 10W40. Its much worse than the Pennzoil 10W30 I tried. Its thicker at both 40 and 100C yet its cold start performance (for me that means slap) is much worse. I even hear more from the motor warmed up. The stuff even looks thin. I have never noticed anything about motor oils in my life until I got this LS-1, damn GM.

RussStang

So amsoil might help the slap some, huh? I am looking to do anything to help get rid of the warm engine slap I have. Originally I ran Mobil 1 5w-30, and the engine definetly had some slap to it. I switched over to European GC based on the result I read about here, and it seemed to get louder. I dumped 4 quarts 10w40 GC/1 1/2 quarts 15w50 GC in the engine just to quiet it down, and it definetly helped out alot. I really don't like having oil that thick in my motor, but this was done during the summer, so it didn't really bother me. Not it is starting to get cold out, and I really don't want this stuff in there. I am probably going to pick up some Amsoil, just to see if that helps. What viscosity should I buy? Around here in the dead of winter temps can easily drop to single digits in the late evenings/early mornings, so maybe 0w30?

dailydriver

If you're concerned about extreme cold flow/start/pump up you cannot go wrong with the Series 2000 0W-30 Amsoil. That being said, now that I have 85K+ on this motor I may try the 5W-40 Amsoil in the spring/summer. Does Redline have any plans to make a 5W-40 or 0W-40??

Camaro99SS

iTrader: (4)

My motor has slapped since I've had it, and I haven't noticed any difference going from Mobil 1 0W40 to German Syntec. Let's get this straight though while we're on the piston slap issure again. If the slap goes away as the engine warms up, it's NOT harmful. GM made them loose for when we all romp on our cars time and again where things get really hot and the pistons expanding. While other quiet motors may be wearing on the cylinder walls under extremem conditions, ours won't be from less friction. This is why any LS1 you tear down, you'll still find the original cross-hatch, even past 150k miles. I suspect that when the first 03/04 Cobra motors are torn down with this mileage, the same will not be true. Those motors are just too tight. Ask any owner who knows their stuff.

Jason