GM Piston Slap

Ross · Nov 30, 2004

I have a 2003 Silverado 1500HD with the 6.0

Mine has a slight knock on cold starts, mostly under load and only in the winter. If I let it idle for about 60 seconds, the sound goes away completely.

I am running M1 5w30. I have not tried any other oils yet, cause my engine likes the M1, no useage etc.. I have heard from someone else on this forum that the castrol start up solved his piston knock, but have not tried it myself.

When I bought the truck, I heard that the 2003's had slight modifications to the engines to help muffle the pistion slap (not cure it or prevent it). That's what mine sound like.

This winter I am running FP in every tank to see if it helps. Should know when the temp go below 0!!

[ December 01, 2004, 01:39 AM: Message edited by: Ross ]

2K2AcuraTL · Nov 30, 2004

As for my 98 Pontiac Transsport's piston slap, M1 has been the predominant oil of choice.
This being said:
-I am using GC for the first time in the minivan, and I must say it is performing quite impressively. (as opposed to my experience with GC in the AcuraTL).
-Swepco was the worst for piston slap.
Jean

twb · Nov 30, 2004

I've got a 1998 Silverado with a 350, the last year for the "old" style 350. In the winter I definitely get what people would call piston slap on startup, and it goes away in a minute or so. I'm a little skeptical about it actually being caused by the piston "rattling" around, as I found it's somewhat related to how restrictive the oil filter is. A Mobil 1 filter or a Purolator Plus, lots of rattling. A "regular" Purolator, much less rattling. Why would oil flow change the degree of piston slap?

About Castrol Syntec: I'm a hard core long term Schaeffer's user, but I've tried a number of oils in this engine. Syntec gave me the best UOA of all of them, and that includes Mobil 1. In case you're wondering, I continue to use Schaeffer's because its UOA analyses were very close to the Syntec values, and it costs me a heck of a lot less.

Vuarra · Nov 30, 2004

quote:

You have not, by way of contrast, claimed or suggested that therefore Syntec 10w-30 is the best thing invented for all cars, cures cancer, prevents nuclear war, etc.

Thanks, ekpolk, but I thought that was either GC or (lubricant deleted due to family values, but contains the letters K and Y)?

haley10 · Nov 30, 2004

quote:

Originally posted by eddyzima:
i am going to put on my flame suite and tell you what works for me. castrol syntec 10w30. i know it is not the best oil in the world, but it sure makes my wifes 5.3 tahoe quiet in the mornigs. ALSO, use chevron techtron in the fuel tank every 1k or so. MOBIL 1 IN ALL WEIGHTS AND MIXES MAKES THESE ENGINES NOISEY. i have also had the best resaults with the cheap purolater filters. the 3.99 ones. -ed.

No flame. It worked really well for me in the past. Maybe with the A5/B5 ratings now, it will become more suitable for somewhat extended drains with better TBN retention. It did cold start really well.

The board is overly critical of Syntec 10W-30. The Syntec Blend and GC edge it out in many applications, however. GC can do longer drains and the Blend has good results and TBN retention for the money. It good stuff, though.

[ December 01, 2004, 02:34 PM: Message edited by: haley10 ]

Ken2 · Nov 30, 2004

twb,
"Rattling" is just a figure of speach. Some cold piston knock is very normal in many engines.

For oil filter concerns, I always like to go back to an OEM filter from the dealership. That's what the engine designer's spec'd for that engine. If makes a difference, then an aftermarket filter can be searched for with the same characteristics. The engine makers do not issue specs for oil filters. The aftermarket filter makers reverse engineer the OEM filters. Often they come up with compromises that usually are close enough to matching the OEM filter.

I don't think the oil filter has much if any effect on cold piston slap. There must be some noise in the valvetrain or somewhere else that is adding to the sounds of the engine with the restrictive filters.

Ken

haley10 · Nov 30, 2004

TWB, interesting. What do you notice with the AC Delco or Wix filters, if you have tried them??

REDDOG · Dec 1, 2004

I have noticed that of the oils I have tried so far, Amsoil 5w-30 (ASL) and the Havoline 5w-30 SM/GF-4 I am currently running seem to have quieted the piston slap in my '98 Vortec 4.3 the best. With the Havoline the slap seems to go away in just a few seconds after start up.

The slap seems most prevalent at temps around 20-40 deg F.

heyjay · Dec 1, 2004

With my 2000 GMC Sierra and Vortec 5.3 V8, I tried the stock AC Delco PF-59 filter and I also tried the Mobil 1 filter, with no difference in oil pressure or noise.

What I found infuriating was that in VERY cold temps (Colder than -20 F) the motor knocked like an old diesel unless I used Mobil 1 0W-30. The problem is, once it warmed up it made ticking noises.

GM can claim whatever they want about their huge problem with "Cold Start Knock" or whatever they want to call it. Piston deposits my a**, why were brand new motors making that noise? They came with deposits from the factory with 20 miles on the odometer??

If you read through www.pistonslap.com you discover that GM had promised a fix, then suddenly changed their minds and told everybody "it's normal, don't worry about it."

Let me guess, if you don't have the noise, there is something wrong with your motor?? HA!

I tried playing with oil viscosity as it was the cheapest - releativly speaking - and easiest thing for me to change.

I figured if the Mobil 1 15W-50 made things much worse, I could always change the oil right away and kiss $45 goodbye. So a person with that nasty noise has little hope of curing it unless they try to experiment.

Or just go to your friendly GM dealer and be told how lucky you are to have a motor that goes, and I quote:

"KNOCK KNOCK KNOCK KNOCK KNOCK KNOCK KNOCK..."

lewk · Dec 1, 2004

my 4.3l vortec in my astro van had a minor ticking noise when warm and an annoying oil starved melody when cold. my solution was to use 5w30 like GM recomends but only 4 qts. the final .5 qt for the filter fill I used 15w40. any top off oil was 15w40 too. i used most of the majors, penzoil, exxon, havoline,etc. dont mix brands i.e., use similar brands for different wts. this works fine all year round in so.cal. much of the noise was abated as well. hope this works for some of you too.

sub_zero · Dec 1, 2004

It's just a noise isn't it? Can you feel the vibration? If you can it's high energy and is something serious. If not just let it go. Is there any serious wear metals on analysis if you've done one?

Craigster · Dec 1, 2004

So far I have tried GC 0w30, and 5qts of Mobil-1 10w30 with 1 qt of Redline 5w30.
With the GC the knocking was louder and knocked even when engine was warm.
Had oil analysis done with both. Mobil-1 was slightly better.
I am thinking about trying Castrol Start-Up 5w30 next.

Your suggestions are appreciated.

BTW.I have 2002 Chev.Silverado 2500 HD.with the 6.0

[ December 02, 2004, 08:49 AM: Message edited by: Craigster ]

ToyotaNSaturn · Dec 1, 2004

I'm not doubting Terry's findings here, I just find it intruiging that only a few oils quiet things down, but none get rid of it, seemingly, at least.

Has anyone tried any of these oils with any luck? straight Delo? PZ LL?
Delvac 1300?
Any 5w-40 Group III synth, Pennzoil, Havoline, Rotella T, etc?
Supertech 10w-30 "Full" synth?
Castrol 5w-50?

carl97ss · Dec 1, 2004

Tonite I'll be putting in 5w-30 Castrol Start-Up in my "Armored Personnel Carrier on cobblestone roads" sounding modified GM motor tonight.

We'll see how it does tomorrow morning.

Terry · Dec 1, 2004

carl, good to hear from you. Did you ever correct the oil consumption issues with the stroker ?

jafo · Dec 2, 2004

I have a 98 firebird with the ls1,approx. 90k.I recently did a decarb with some seafoam(gm top end cleaner works too)and no more noise at startup.I also followed up with a bottle of redline si1 in the tank.I wasn't trying to get rid of the noise, just doing a decarb as part of regular maintenance.Getting rid of the noise was a definite bonus.

quote:

Originally posted by Ken2:
There are two separate causes for the noise GM calls CSK (cold start knock).

One is the piston rattling around in the bore.

The other is carbon built up on the top of the piston and on the head. A warm engine expands enough so the piston and combustion chamber don't knock their carbon together, but a cold engine might have contact. A very good combustion chamber cleaner helps.
http://www.pistonslap.com/tsb/010601028A.htm

Ken

buster · Dec 2, 2004

Great post Terry. Always wondered if sound was related to wear.

eddyzima · Dec 2, 2004

quote:

Originally posted by Craigster:
So far I have tried GC 0w30, and 5qts of Mobil-1 10w30 with 1 qt of Redline 5w30.
With the GC the knocking was louder and knocked even when engine was warm.
Had oil analysis done with both. Mobil-1 was slightly better.
I am thinking about trying Castrol Start-Up 5w30 next.

Your suggestions are appreciated.

BTW.I have 2002 Chev.Silverado 2500 HD.with the 6.0

I ALSO HAVE A 2002 2500HD WITH THE 6.0. GREAT TRUCK. BUT THAT 6.0 IS A TICKY CRIDER.

I ALMOST WORE OUT THE DRAIN PLUG ON THAT THING. THAT IS HOW I CAME ACROSS THE SYNTEC 10W30. I HAVE ALMOST TRIED ALL BRANDS OF OIL AND FILTER. DINO OIL MAKES IT QUIETER ON START UP BUT TICKS WHEN WARM AT IDLE. THE CASROL STARTUP KEEPS IT QIUET AT START UP BUT TICKS WHEN WARM AT IDLE. AND THE SYNTEC BLEND HAS START UP NOISE AND THE TICK AT IDLE. BUT I HAVE RUN 2 CHAGES WITH THE NEW SM SYNTEC 10W30 AND NOCK ON WOOD NO NOISE EVER. I KNOW ITS OVER PRICED FOR THE QUALITY, BUT SURE IS NICE WHEN YOUR 30,000 $ TRUCK IS QUIET. ALSO I HAVE TRIED ALL OIL FILTERS. AND THE CHEAP PUROLARE IS THE QUIETEST. I DON,T KNOW WHY? I HATE TO BABAL ON BUT THIS TRUCK DROVE ME CRAZY. AND I SURE HOPE THIS HELPS YOU. BTW I TALKED TO CASTOL ABOUT STARTUP AND THEY WOULD NOT SAY HOW IT WORKS BUT THEY TOLD ME SYNTEC SM HAS MORE OF THE GOOD STUF. WHAT EVER THAT IS ?

[ December 02, 2004, 08:17 PM: Message edited by: eddyzima ]

Blue99 · Dec 2, 2004

per Al

quote:

I can tell you that Mobil 1 10W-30 doesn't help.

per Ed

quote:

MOBIL 1 IN ALL WEIGHTS AND MIXES MAKES THESE ENGINES NOISEY.

I have the same opinion based on running M1 10W-30 last winter in my 99 Silverado with the 5.3L Vortec.

It's my speculation that the cold start knock is louder with a PAO based oil. Similar to the lack of seal swell with PAO, the combustion chamber deposits may actually get harder in the presence of PAO as opposed to a dino oil.

These deposits are located both on the top edge of the piston & ring and on the combustion chamber. As the engine warms up, the deposits soften up & the noise goes away.

A minor film of oil will reach the deposits thru the piston rings and this can aid in keeping the deposits soft & reduce the knocking noise at startup.

My current thoughts are that the natural solvency of GRP I or a dino HDEO, or possibly Esters is what will help reduce the hardness of the deposits and reduce the CSK noise.

BTW, I really like the performance of the 5.3L engine and am willing to put up with the 20-30 seconds of slight knocking during a cold start!

Terry · Dec 2, 2004

TNS, Doubt me please, someone besides the wife needs too ! Trust but verify..

Opinions and observations on noises and lubes used.

Specifically M1. M1 is a very "clean" fluid that allow lots of sound transfer because of its formulation.

Sound is not a good measure of a oils capability to lubricate unless you are a highly trained mechanic ( that still has hearing left) and a good stethescope.

Until soluble moly was added to their mix a few years ago ( note amazement in the industry) there was even more sound transfer.

Really great sound insulating lube fluids are not always good lubricants. Fluids that use a PTFE dose insulate sound very well and MAY lubricate a engine very poorly. Heavier vis fluids do the same and may sacrifice lubrication in certain applications.

Generally the lighter the vis of a lube the more you will hear things inside.

GM Piston Slap

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