GM Piston Slap

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Hey Terry!!
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I never got the consumption problem resolved. My engine builder rebuilt the engine May 2003. He found nothing that made sense for the consumption. It was definately getting by the rings and appears to be doing the same. He went with a Z-06 "type" ring package, measured and rehoned the cylinders but, it has not helped. Static compression is good at 203psi across the board +/-3 psi and each cylinder leaks down about the same at 5-6 psi after 5 minutes.
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During the rebuild we replaced the cam due to excessive wear on 2 of the cam lobes. We replaced all the lifters (Comp Cams "R"-
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)rockers and valve springs. I still use 1 quart per 1000-1500 miles depending on oil weight. Engine dyno'd strong and continues to run great. Over the last 6 weeks been on the road to the tune of 5,000 miles. Running 80 mph+ I averaged 25.2 mpg with 4 tankfulls over 26 mpg! I'm a LC user now.
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Terry, I have not had an oil analysis done since the last one you did for me. Considering the oil usage, would it be beneficial to have one done w/ the Castrol Start-Up after 5,000 miles? (7 quart capacity)
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As for the Castrol Start-Up this morning (28 degrees F), there was a difference in sound vs. Mobil 1 5w30. In my case, I did not expect the piston slap to go away
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but, it did quiet things down enough for me to notice.
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My 98 chevy truck with the 350 has startup knock and it sometimes has a tick when the truck is warmed up. When I used to use Mobil 1, the sounds were a lot louder. With the Chevron Supreme, its not as loud and doesn't seem to last as long. This truck has been making this noise since about 36,000 miles and now I'm at 73,000 miles. It used to bother me but now I just don't care. We will see if it ever becomes an issue.

Wayne
 
I have a '98 GMC 454 bought new 128k at present...piston noise from day one..found this site and started to experiment with the HDEO...PZ LL 15-40 seems to work the best in the summer with a Baldwin filter and 89 octane fuel...also a K&N air filter...this winter I put in M1 Truck & SUV 5-40 with the Baldwin filter and 87 octane ...NO statrup noise what-so -ever...go figure...I'm going to run this oil in the summer and see what it does..additional bonus is an increase in milage from 13 to 15 MPG not pulling anything...if I'm lying, I'm dying
 
eddyzima-

Glad to here that you found a combo that works!
Thanks for the info.

I will try 3qts of syntech 5w30,and 3 qts of 10w30 for the winter,and then go with straight 10w30 for the summer.
 
How about a high moly content oil, such as the new SM/GF-4 Valvoline Maxlife with 300 ppm of moly?

Based on Terry's comments, the moly should help deaden the fluid's ability to transmit noise.

I'm about 2 months away from my next oil change & would like to explore the moly effect for use in my 5.3L.
 
quote:

Originally posted by Terry:
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.


Terry, why then if, M1 is a cleaner, less sound deadening product, when I use M1 xW-30 compared to an equivalent dino (say Havoline for example) on my little Saturn, does the NVH come way down? Is it just due to the fact that it's PAO compared to a flat-rate group II?
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Castrol syntec did help quiet the piston slap, but it is still there.

I think Terry was right. In most cases no oil is going to eliminate the noise, but it can make a big difference in how loud it is.
 
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