My 03 Z06 engine piston slaps loudly for a few minutes on cold start, I wonder if a low mileage LS engine has the same issue or if it’s a wear over time affair my car mileage is a little over 57k btw.

 

Piston slap is not terribly common are you certain that is is piston slap (even if it is it will most like never hurt anything). But lifter related issues are much more common and could be something that changes with engine temperature.

 

yep agreed, mine does it on a cold Start all the time but once warmed up it goes away

 

What oil weight are you using ?
Also I hate to ask but are you on top of keeping it at the right level?

 

Piston slap is primarily a piston to bore clearance issue. Sure, brand new engines can exhibit it, especially if the engine was built on a Friday afternoon. Obviously, an older engine whose clearances were borderline can develop piston slap as the miles rack up. Generally, it's more annoying than anything else. In other words it is not typically indicative of an impending failure of any kind and engines so affected routinely go many tens of thousands of miles with no issues.

With an aluminum block the slap tends to go away upon reaching operating temperature. With a cast iron block, they tend to do the opposite, getting louder as the engine warms.

 

My 2002 Base has piston slap for sure. Upon start up cold (the 1st big vroom when it fires up) I don't hear it, then it settles into the normal cold startup idle it's loud to me.
below 30 degrees it's real loud 55-60 not to bad 70-80 I can still hear it, but just. The sound stops at about 100 degrees oil temp.

 

I’m running Valvoline advanced sinth 5w30 and yes I periodically check level to keep it on top

 

I can confirm it’s piston slap that noise has nothing to do with lifters

 

Piston slap in cold LS engines are a very common issue not just in Corvettes but any vehicle with an LS engine. It generally goes away shortly after cold start and generally has little impact on the engine line as a whole if you care properly for the engine.

Generally as long as it goes away quickly you will be fine.

 

My 98 has being doing it for 26 years. No problem yet.

 

Most of the trucks and Camaros too.

 

Go for 40 weight. This is helpful in silencing the factory valvetrain. It won't resolve piston slap but it may provide a bit more barrier between surfaces.

 

You so have to watch on dome engines going to thicker oil. It can restrict flow to different o ports on the engines like the oil squirters that cool pistons or the V6 cam adjusters on some engines.

Older cars can also have blocked passages.

Nothing specific on the LS but something to consider. People have lost a rod or main with a change.

 

^ This
The metering orifices in hydraulic lifters, for instance, are designed for the use of a specific oil viscosity. Deviating too far from the recommended viscosity oil can have a meaningful effect on how your valvetrain operates.

Also, thicker viscosity oil does not necessarily provide better wear protection. First of all, lower viscosity oil more easily penetrates between moving engine parts and modern additive packages provide better wear protection than your grandfather's engine oil. Modern 0W-8 oil, properly formulated, can provide better engine protection, assuming that your engine's internal components have the appropriate clearances and calibrations to use it. Just because an engine oil has the same flow characteristics of water, this does not mean that it has the same lubrication properties of water.

If the theory that a higher viscosity oil will quiet an aluminum engine with piston slap (where the slap is typically more prominent when cold), then it would seem to me that you might want an oil with a higher resistance to flow when cold. Therefore, instead of going from a 5W-30 to a 5W-40, a 10W-30 may be a better approach? This assumes, of course, that you don't live in a geographic area where a higher cold viscosity will interfere with your ability to start the engine in Winter. That said, I have never tried this approach, so I wonder if anyone has actually tried this strategy and, if so, what your results were.

 

Well this is where all this Dexron rating are coming from. The auto industry is using oil for much more than just lubrication in modern engines.

They adjust cam timing. Cool pistons and other key parts with oil They lube turbo bearings and more. Because of all the things they are doing now they need specific things in oils to do it.

There has been difficulties between the oil MFGs and the Auto MFG not always agreeing on what is needed so they came up with the rating to force the oil companies to meet their specs.

In old engines there was just a few basic things oil did and most of it was to lube the crank, rods and cam. Also to leave enough in the cylinder to stem wear and valves.

The LS is one of the first engines to start to use these measures. They cool the pistons with oil due to the higher compression to help stop detonation of higher cylinder temps. Other engines do even more now.



I have sat in with Lake Speed in some training and he knows his stuff. Thicker is not always better. If you want to make changes it is worth a call to the oil company you are using for recommendations. Just changing today is not always a good thing.

Oil has become very high tech and also todays engines the way they are build need them.

 

agree I don’t want to play with oil viscosity and I trust GM engineers they are smarter than me for sure

 

Yes the simple things are not so simple anymore. We all really need to keep up with even the basics.