Piston slap in car - what oil?

[fishman]

Some of you might have read the thread I posted on the valve train noise in my Impala's 3.4 l engine. After using some motor flush and doing some reading, it appears that it might in fact be piston slap (i.e. bore too large and piston too small). Anyway, the car calls for 5w30 or 10w30. It seems to me that a heavier oil might quiet the piston slap, which is only a problem for 5 minutes or so at cold startup in temps of 40 degrees or less. It's not really that big of a deal to me, but if I can reduce the problem, that would be great.

Any ideas? /forums/images/graemlins/confused.gif

 

[bandit67]

Piston slap is an issue in some GM motors. I know they've had issues with the 6.0L V8's, and have come up with supposed fixes under warranty.

Not sure if your motor has warranty up to 100k, but you may want to check in with a dealer, and not necessarily the one that the previous owner used. They may have some suggestions for you. Until GM fessed up to the piston slap issue, the standard response was "that's normal", but since admitting to the issue, you may have a better chance of getting some sort of advice from the dealer service dept. You can also go online and get the GM toll-free customer service center number and give them a call and see what they have to say.

Good luck.

 

[mark1]

Years ago (1976) I had a Merc.Bobcat(Ford Pinto) with the 4 cyl.engine it had piston slap on cold mornings like crazy.No type of oil or weight seemed to help.Ford fineally admitted they "Forgot" to dril oil passage holes in the connecting rods to squirt oil on the cylinder walls thus preventing the slap.They pulled the engine,and replaced the rods which fixed the problem. There are now many newer types of oil and additives,Not sure if you'll find any that help. /forums/images/graemlins/confused.gif

 

[JimR]

The Ford problem was a biggy back then. I changed out many 4cyl motors that were junk with less than 10k on them. The cylinders were wiped out due to lack of lubrication.

As for the Chevy piston slap. I did tell you that my GM Service Manual states that the 4.3 will have piston slap for up to 2 minutes when cold. This is bull-crap in my opinion and bad machining problems. You could try STP oil additive with 20-50 motor oil. I see that you are in TX. and that would not mean a hard starting problem due to the cold.

 

[Dargo]

I don't know how many miles you have on your car, but I had good luck on an older car with quite a few miles on it by going with just straight 30 weight oil and also adding "motor honey" to it. I changed it every 3000 miles with the same mixture. It only made noise for a couple of seconds and I never had a problem afterwards. It may not be the best method, but it worked for me.

 

[geneP]

My Toyota pickup 4 cylinder with 170,000 miles on it has the slap for a few minutes when first started cold. I first noticed it after I changed the timing chain at about 145,000. I don't see how the chain could affect it, maybe the chain rattle was masking it till then. I had always run 10w-30 but changed to 20w-50 in an effort to slow it down, but couldn't tell any difference. I just try to keep it out of the rpm range where it slaps until it warms for 3-5 minutes.

 

[Cook123]

make sure you use anti drainback filter. also my driveway is on incline and if i park front end down no slap, frontend up for a few days and it slaps and rattles. please only use stp as a last resort and stay with the same viscosity oil you have been running.

 

[John762]

dont knock stp have used it in my 89 chevy c1500 with 4.3 for 239,000 miles and only have replaced valve seals which were the o-ring style(junk), they were replaced with the bonnet style at approximately 110,000 miles

 

[Outlander1]

Sitting in the drive at the moment are an '05 Forester, '05 Malibu and '04 Mitsu Outlander. All have piston slap when cold. I have looked into this with all concerned service departments and the answer is the same in all cases. The engines are set up loose to avoid friction. Some of them even have the teflon coated skirts. I was told it's about fuel economy. Personally I like quiet. Times change I guess .....Just so they do the required 100000 miles.

 

[Zork]

I had a toyota with that same problem. it was covered under warranty and the vehicles that werent went 100k + miles anyway. After 240k on my replaced 22r 4x4 pickup you could here it faintly. (just a note, I used Quaker State in that truck) Changed to a lighter oil and it was noticibly quieter. I also had a chev celeb once and a piston slap type noise came and went from time to time. I pulled it apart and found 3 of my wrist pins frozen. Replaced pistons and had no more problems. /forums/images/graemlins/grin.gif