94zLT1

i have the infamous piston slap at cold startup and ALSO at operating temp ..just a little quieter but its still there when hot..i am running 5.5qts of mobil 1 syn 10W30...what weight could help me lessen the noise?

from what i have read it seems this piston slap/noise should not be heard/occur at operating temp..but mine does..should i worry? car has 42K on it.

also it runs strong.

blacknight

Unless your using up a lot of oil it's nothing to worry about. A lot of ls1 owners use 50% 10w30 and 50% 20w50. That or 10w40 might help. I starting using non-synthetic oil and my piston slap was greatly reduced.

frmula1

once and for all


WTF is piston slap exactly??
and is it something to worry about?

94zLT1

blacknight i am thinking of switching to non syn. to help the slap and noise. the engine sounds like shi^ at all times what brand and weight do you suggest. thanks

and frmula-slap is the piston smacking side to side against the cylinder walls..GM says its fine and harmless..but many are weary

94zLT1

can anyone answer my last question?

daves02ss

I have piston slap to and a chattery valve train, it gets better at operating temp. If your car is running strong I would not worry , due to the fact that the motor is all aluminum I think it makes more noise than usual(iron block = quieter absorbs sound better). I also consume about a quart of oil every 1k miles, went up to 10w30 penzoil synthetic and it seems to help a little, my car runs strong too. Some people have torn down their motors(dealer/warranty) for a re-ring of pistons and piston replacement but still have the problem. I think these symptoms are just the personality quirks of Ls1 motors, every mass production motor has some short coming.

94zLT1

i am thinking of switching to non syn. to help the slap and noise since i have it even at operating temp and it sounds like a rod knocking constantly. i have heard it works for some to run thicker..

since i JUST did my oil change and put 5.5 qts of mobil1 10W30 in there..can i just leave the filter there and drain say 2 qts of oil from the pan and then fill with a thicker weight? can i mix 2 synthetics oils? can i mix synthetic and no-synth? i just want to drain like 1 or 2 qts of the 10W30 and add something to thicken it..HELP

or should i just drain the whole thing (except the filter) and run a thick no synth oil? if so is it ok to mix the new non syn with the say 1/2 qt that will stay in the filter?

what should i do? what brand and weight do you suggest to add after draining a few quarts. thanks

fly89gta

Do a search a what oil people run. You'll find a lot don't run 10w30. Furthermore don't switch to conventional for the sake of piston slap. It's just a thing these motors do, you can't get rid of it unless you rebuild it.

Like I said, I'd do a lot of post/thread searching before just taking the initiative to just switch the lifeblood of your motor.

SSpdDmon

I switched to Castrol Syntec after reading some oil guru's post on another forum. He had sent the stuff off for analysis and it came back looking great each time. So, I run the Syntec 5w30 in mine and it did quiet down some of the piston slap. He claimed it was because Mobil 1 is on the thin side of 5w30's whereas Castrol is almost thick enough to no longer be classified as a 5w30. Needless to say, I won't be going back to Mobil 1.

frmula1

does having the ls6 block, in your guys's knowledge relieve the ls1 piston slap problem in anyway?

fly89gta

Yup, the German stuff is good stuff Just hard as hell to find lol

94zLT1

im running 4 qts of mobil1 10W30 and 2 qts of mobil1 15W50.
now that i think about it i dont know why some people would say there slap noise is lessened with thicker oil bc doesnt thinner oil get into the galleries and bore/piston easier?

my slap is horrendous sounding at full operating temp 210 but seems to only be heard at 1000rpm to 2000? I thought it is supposed to go away at oper. temp? it sounds terrible. hot at idle it really can barley be heard but once i give it gas and it rises to 1K rpm through 2K it is terrible. should i be concerned?

lbls1

No!!