I switched to the recommended 5W-30 and the noise was reduced at start up. I do not consider the noise other then normal for an engine, a little louder then our previous 454.
I believe that most of the noise is associated with the valve train and the lighter weight oil gets to valve train quicker, it probably drains quicker as well. I have not heard any piston slap in our 2003 8.1.
Also the tolerances are tighter then say the old 454 and the use of ligher weight oils better lubricates such engines. I have not tried synthetics in this engine, but would be interested to know if there is any difference.
i have a 2000 7.4l with 111,000 mi.on it. ran full synthetic 20/50 over the summer when fall came i swithed to mobil 1 10/30 the next day the slap was so bad i dumped it in the drain and put 20/50 in it.
I did some research on the 8.1L oil consumption and most of the big truck forums are reporting good luck with 180F thermostats. I'm making the change shortly. Also, my 2002 LS1 Camaro has the same startup ticking noise as the 8.1L, although it isn't fond of oil. In both cases, synthetic cut it down significantly.
2007 Thor Vortex 22FB
2002 Chevy K2500HD CrewCab LT 8.1L/Allison
Equal-I-zer/Prodigy/Equa-Flex
7 MPG towing, but it goes faaaast
Not uncommon...my LT1 Caprice slapped for about 10 seconds in cold (<15 degrees) weather. It used no oil (always 5W-30) in the 50,000+ miles I put on it.
The loudest slapper I ever heard was the ZZZ 300HP crate 350 in my friend's 1979 Chey K-20 pickup. On the initial startup, he thought we'd forgotten to fill the oil pan, and his mother (we'd appropriated the garage for the weekend to swap engines) thought somebody was knocking on the door. It's gone over 65K without a problem--still slaps cold. This was very common on early GM ZZx (ZZZ, ZZ1, ZZ2) crate 350's. The ZZ3 and ZZ4 used different pistons which didn't slap.
John
1984 Ford B-700 school bus conversion, Thomas body
A bunch of other vehicles
3 nutty cats (Maya, Vierna, Briza)
One lazy dog (Marmaduke)
One wife (Liz)
"A wasted youth is better by far than a wise and productive old age"
-Jim Steinman
I put in the 180 F thermostat in my 8.1L. In short, I think the truck was MUCH happier.
We did a lap of Oregon: I-84, 101, 42, and 97. The temperatures were moderate - high of about 90 on the last day. When I got home after 1000 miles of hard towing, I was down less than half a quart. I didn't get the ignition retard effect but once or twice and my last two tanks were over 8 MPG (vs. the ~6.5-7 I usually get) with the same speeds over the same route. We looked at a 8.1L powered motorhome that was on the same trip and I noticed they had much more in the way of cooling fans. My predator programmer showed steady 185F on the ECT every time I plugged it in.
I sold my 2001 5.3 2 years ago with 115,000 miles on it with no noise (bought a truck that rattles all the time ). My brother's 2000 5.3 knocked at startup almost since new. When he passed away the truck had 246,000 miles and still ran great using very little oil and still "slapping".
There is no place to boondock in Colorado. Repeat after me, there is no place to boondock in Colorado.
2006 Dura Max LBZ now in the driveway
Reese 16K slider-rocker
26ft Thor 5th wheel
2 Polaris Sportsman 500s
64'6" nose to tail when "Double Towing"
here is what has been reported over at the Suburban forum....
Oil consumption has been attributed to two things. All ICE's have oil
misting inside. Marry that with the dumb intake manifold gasket design
and the intake will draw in oil mist. Solution has been to change out
the intake manifold gasket to the 'new' design (DeathCool also plays to
eat the old gasket O ring seal). Other is that they used stainless rings
and they take anywhere from 40K to over 60K miles to seat (IIRC) and
then seal properly.
Slap has to do with the 'new' coatings and the subsequent thermal rate
of expansion differentials between the different materials..till they
normalize thermally. Till they expand to tolerance, the space allows
the piston to 'slap' the cylinder wall. Other is as stated before, there
is carbon build up in the CC (combustion chamber) that the piston hits
at TDC.
No major problems other than annoyance has been reported over there.
-Ben Picture of my rig
1996 GMC SLT Suburban 3/4 ton K3500/7.4L/4:1/+150Kmiles orig owner...
1980 Chevy Silverado C10/long bed/"BUILT" 5.7L/3:73/1 ton helper springs/+329Kmiles, bought it from dad...
1998 Mazda B2500 (1/2 ton) pickup, 2nd owner...
Praise Dyno Brake equiped and all have "nose bleed" braking!
Previous trucks/offroaders: 40's Jeep restored in mid 60's / 69 DuneBuggy (approx +1K lb: VW pan/200hpCorvair: eng, cam, dual carb'w velocity stacks'n 18" runners, 4spd transaxle) made myself from ground up / 1970 Toyota FJ40 / 1973 K5 Blazer (2dr Tahoe, 1 ton axles front/rear, +255K miles when sold it)...
Sold the boat (looking for another): Trophy with twin 150's...
51 cylinders in household, what's yours?...
I can't imagine that I'm going to get less at trade in because of the piston slap. Dealers know that these noises are normal when the engine is cold.
And we all know about the high integrity and morals of car salesmen.
THEY know it is not a problem, but if they can convince the poor customer trading it in that it IS a problem, that's several more thousand dollars that the dealer pockets.
Now that same salesman, when reselling the truck, will have all kinds of documentation from GM to show the new buyer that the knocking is NOT a problem.
And the cycle repeats...
Paul (Mouse)
2007 Flagstaff Shamrock 17 Hybrid (heavily modified for boondocking and winter camping).
2007 Dodge Dakota Quad Cab 4x4, 4.7L HO, factory tow, 3.92 gears.
Equil-i-zer Hitch, Prodigy.
Yamaha EF2400 Generator (quiet, cause I care!)
My 8.1 used 1/2 quart of Mobil 1 driving fully loaded (9,500 lbs, non-towing) from NJ to Lake Buena Vista (Disney World) in hot weather and AC blasting. It has zero piston slap and runs cool with cruise-control set at 75mph in 70mph zones.
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). My brother's 2000 5.3 knocked at startup almost since new. When he passed away the truck had 246,000 miles and still ran great using very little oil and still "slapping".
