Knocking, switch back to dino oil?

quiksilver9531 · 10-16-2005, 12:00 PM

When i got my transam it didnt make any noises, but 2000 miles later a lit bit after i switched to synthetic I can hear knocking, I bought the car with 69k and I beleive it was ran on dino oil, I switched to mobil 1 at like 70k and shortly after my motor got louder, I can hear knocking, not loud but you can hear it, Im pretty sure its piston slap, but it doenst go away when my motor gets hot, it gets quiter but its still there, now my question is should I go back to regular oil and see if the slap goes away? and is it normal to still have slap/knock at hot operating temps? Thanks

BlackHawk T/A · 10-16-2005, 12:02 PM

It's normal...mine started doing it too...sounds like a Diesel...but theres no way in hell i'm switching back.

quiksilver9531 · 10-16-2005, 02:07 PM

but why use synthetic when I could use regular oil and not hear all the noises, the knocking just worries me and if i dont hear it then it wont bother me, is it ok to switch back after using synthetic? bad for the seals?

BlackHawk T/A · 10-16-2005, 02:38 PM

Originally Posted by quiksilver9531

but why use synthetic when I could use regular oil and not hear all the noises, the knocking just worries me and if i dont hear it then it wont bother me, is it ok to switch back after using synthetic? bad for the seals?

The Synthetic is going to protect your engine far better than any dino oil could. The "Piston Slap" is a known issue and no engine damage has even been reported or tied to it in the millions of miles these cars drive every year...

Yeah its annoying and I wish it didn't exist, but mine started after I switched to Amsoil 0-30 and I have far better faith in this oil to protect and lube my engine than the previous owner's Conoco 10-30. It will probably increase your mileage a bit too because your engine no longer has to work against the heavy dino oil and sludge buildup that will be cleaned out.

**MadSeason** · 10-16-2005, 10:50 PM

That knocking is the sweet sound of your engine working easier, stick with the synthetic... unless you're one of those guys who turns up the radio when you start hearing funny noises instead of looking into them.

**Sarge** · 10-17-2005, 06:59 AM

The sludge/crap build up from dino oil does buffer engine noise....and it also restricts flow of lubricant getting to vital engine parts.....synthetics will clean this crap out and yes your engine will sound differently......now I am not bashing Dino oil here......many folks clean their engines with AutoRX or LubeControl on a ongoing basis and run high quality dino oil with much success...some add a quart of Amsoil or RedLine to dino oil for the additive packs....
Once an engine is cleaned....a person can run Dino oil with reasonable OCI's and achieve great results.....or you can run synthetics and don't worry about it....

As for GM and the piston slap...or as some call it "Like a Knock".....I
ve seen folks put in 20-50 weight oil trying to stop it......it is just a fact of design on our motors....mine sounds like a Peterbuilt sitting at idle.....it isnt a bent rod...or an oil issue...it is just how it is.....

quiksilver9531 · 10-17-2005, 02:43 PM

wow that sucked, i took out the mobil 1 and put in regular oil, and it made the knocking noise 2x louder, which I'm sure isn't piston slap now, it sounds like its coming from up top, what could be causing this? I'm thinking a lifter, but what would a loose rocker sound like? I'm real pissed that I just drained out the mobil 1 with only like 300 miles on it and put in a regular oil which made the noise louder..wtf? I have real good oil pressure so I would rule out bearings or anything like that. Any way to test lifters and stuff like that? i think im just gonna take it to a dealership and have them diagnose it and i'll fix it

**Sarge** · 10-17-2005, 02:46 PM

Mobil 1 cleaned some crap off of you internals.....so yes....putting dino in aint gonna change nothing...I bet there is nothing wrong...LS1's are not "quiet" motors.....

**Zboner** · 10-17-2005, 02:59 PM

Sarge i didnt know the made LS1 motors? lol is it electric????HAHAHA LOL

**Sarge** · 10-17-2005, 03:03 PM

Originally Posted by Zboner

Sarge i didnt know the made LS1 motors? lol is it electric????HAHAHA LOL

**Zboner** · 10-17-2005, 03:05 PM

motor=electirc
engine=internal combustion

**warpwr** · 10-17-2005, 03:18 PM

Originally Posted by Zboner

motor=electirc
engine=internal combustion

True, but common usage dictates otherwise. Motorcycle for example.

Engine can also be external combustion. Steam locomotive.

**Sarge** · 10-17-2005, 04:23 PM

Originally Posted by quiksilver9531

wow that sucked, i took out the mobil 1 and put in regular oil, and it made the knocking noise 2x louder, which I'm sure isn't piston slap now, it sounds like its coming from up top, what could be causing this? I'm thinking a lifter, but what would a loose rocker sound like? I'm real pissed that I just drained out the mobil 1 with only like 300 miles on it and put in a regular oil which made the noise louder..wtf? I have real good oil pressure so I would rule out bearings or anything like that. Any way to test lifters and stuff like that? i think im just gonna take it to a dealership and have them diagnose it and i'll fix it

From Mobil 1 themselves.....FAQ section...
Question:
Switching to Synthetic Oil in Higher Mileage Vehicles
Does switching from a petroleum-based oil to a fully synthetic oil on a higher mileage vehicle (75,000 miles) have any harmful effects? I've heard that the synthetic oil, because it is cleaner, may actually loosen some of the build-up from petroleum oil and has the potential of clogging the pump. Is this true or does one simply need to change the filter more frequently for the first few thousand miles after switching? Thanks
-- Michael Ritzke, Appleton, WI
Answer:
When switching to Mobil 1 in higher mileage vehicles, we recommend an initial short (2,000 to 3,000 miles) oil change, both oil and filter. This will allow Mobil 1 to clean some of the engine deposits that have accumulated over time. Following this initial short oil change, continue with your normal oil change interval.

quiksilver9531 · 10-17-2005, 06:24 PM

Its definatly not a normal sound

**Sarge** · 10-18-2005, 05:03 AM

Originally Posted by quiksilver9531

Its definatly not a normal sound

OK....Not arguing it is or isn't.....If you have no arcing plug wires...exhaust/head gasket leaks....then yes....the next step is go inside and check it out....