Best oil for piston slapping Silverado?

[Yuk]

Haven't heard it myself, but my friend has a noise issue with her Chevy Silverado. She describes it as a diesel engine sound for a couple of minutes after cold start up. This description sounds to me like legendary GM, V8 piston slap.

If so, which oils have worked well to quiet these savage beasts.

Btw, I told her if it is piston slap, that it shouldn't affect the life expectancy of the engine and that it's just annoying. Was I wrong?

 

[cfromc]

The best I've used so far has been Mobil 1 10W-30 High Mileage. That is compared to Amsoil XL 5W-30, ASL, TSO, and Autozone 5W-30. I've heard that Amsoil HDD 5W-30 works too but I haven't used it personally (yet). If the slap lasts for under a couple of minutes then it is considered "normal". However if the slap never really completely goes away, there is a problem that should be addressed if still under warranty.

 

[IndyFan]

This is a carbon issue, not piston slap. You are lucky if a brand or weight of oil stops it. It can be cleaned, but it returns. It won't hurt the operation or durability of the engine.

 

[jmb106]

Try some GM top end engine cleaner or seafoam treatment to cleanup the combustion chamber, she might have some carbon buildup. I switched to 5w20 & have not heard mine make that noise since.It won't effect the life of the engine as the pistons have very short skirts & they rock in the piston bore until they warmup.

 

[XPR]

If its a carbon issue, you might want to try a bottle of Amsoil PI fuel additive. See if that helps.

 

[SargeGTO]

The slap in the LSX engines is due the shorter piston skirt allows a slight piston "rock" in the cylinder. As the cylinders coat with lube it pretty much goes away. Doesn't hurt a thing and these engines last very well and perform very well. So there is nothing to "fix"....just bothers some folks.

 

[Yuk]

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The slap in the LSX engines is due the shorter piston skirt allows a slight piston "rock" in the cylinder. As the cylinders coat with lube it pretty much goes away. Doesn't hurt a thing and these engines last very well and perform very well. So there is nothing to "fix"....just bothers some folks.

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Is it common for this noise to occur well after break in? She bought the truck at around 80,000km, with no noise. Now, at around 125,000km, it's making noise.

 

[SargeGTO]

Yeah...the piston skirt length doesn't change with mileage.

 

[SargeGTO]

But with that many miles she may want to run some top end cleaner....I've seen the slap "come and go" based on many factors...temps/oil/oil filter choices etc.

 

[ThirdeYe]

I've used different types of oil in my mom's 3.1 slapper, and nothing seems to quiet it but it runs great after we got the intake manifold gasket replaced

Tried: Valvoline 5W30, Mr. Goodwrench 5W30, Mobil Clean 5000 5W30, Valvoline Maxlife 5W30.

 

[Yuk]

Thanks for the info, I'll let her know.

 

[BuickGN]

My GN with forged JEs and .004 piston to cylinder clearance and a slightly shorter skirt piston slaps bad for a minute after startup.

I've had great luck with regular dino oils over synthetics. I can't give any scientific reasons but there's a noticable difference in the noise level at startup with roughly the same weights.

The only thing I do is wait for the pistons to expand enough to quit knocking before I put a load on the motor. It's fine for my weekend toy. Might be annoying on a daily driver. If it makes you feel any better, I swapped heads after 10K miles and the cylinders still had the hone marks and it looked like the engine had never been run.

 

[Merkava_4]

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Yeah...the piston skirt length doesn't change with mileage.

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^That's just flat out mean Sarge.

My theory is that a straight 30 might help take up some of that .004'' (or whatever it is on this Chevy) clearance on start-up by not draining off the skirts during off times. Myself being as stubborn as I am, I'd even try straight 40 before I pulled those pistons out.

 

[Mokanic]

Quote:

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Haven't heard it myself, but my friend has a noise issue with her Chevy Silverado. She describes it as a diesel engine sound for a couple of minutes after cold start up. This description sounds to me like legendary GM, V8 piston slap.



If so, which oils have worked well to quiet these savage beasts.

Btw, I told her if it is piston slap, that it shouldn't affect the life expectancy of the engine and that it's just annoying. Was I wrong?

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Piston slap is completely normal in GM products. Actually, GM says it doesn't exist if you turn the radio volume up.

 

[Merkava_4]

I'd be trying a variety of oils until I found one that works. I know one thing for sure; the SAE 40 sure cured the piston slap in my Briggs & Stratton.

 

[Triple_Se7en]

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Re: Best oil for piston slapping Silverado?

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From reading the posts here for the past 4-5 years, GMs seem to like Pennzoil. My vote is for the yellow bottle in 5W-20 - with a silver bottle of VSOT included. Change every 4K.