rattle pistons oil change?

[quick_16]

This question is from a drag race forum I post on from a user. It was on a thread disusing the value of M1 and went down hill from that...lol


I would appreciate any suggestions.

Quote:
What do you think would be a better replacement for my 2007 Trailblazer SS- LS2? I've been using the 5w30 Mobil 1 for the first 50,000 miles. The pistons have always rattled until temp comes up, but not an oil burner...guess I'm lucky.

The Colonel

 

[demarpaint]

I'd like to see the whole thread. I guess there are Mobil 1 bashers everywhere.

 

[tig1]

I thought GM fixed their piston slap problem around 2004? At any rate my brother in law has a 02 Chevy truck and Mobil 1 5w30 Extended Performance helped his piston slap over dino. What did GM say about your problem?

He still has some rattle on start, but not as bad as it was.

 

[quick_16]

I'll post it after I see a few unbiased comments to the question I asked

 

[Bror Jace]

quick_16, a lot of vehicles have 'piston slap' which is what's described above. Engine makes a loud knocking or rattling noise that disappears when it comes up to temp. The colder the louder the noise.

In many cases it's harmless ... a little wear on the piston skirt and the sides of the piston slap against the cylinder when it's very cold (shrunken) but goes away when hot (expanded for a tighter fit).

Mobil 1 tends to be formulated on the thin side and seems to make the most of this phenomenon (the loudest). Using a thicker oil will help deaden the sound ... but it may not be better for other parts of the engine. Loads of moly seems to help as well (Schaeffer, Red Line & others).

In short, this topic has been discussed on BITOG going back to 2001 and its inception.

 

[tig1]

Originally Posted By: quick_16
I'll post it after I see a few unbiased comments to the question I asked



It's hard to say what you are looking for, but the problem is mechanical. Oil doesn't cure engine design problems. Some types of oil may dampen the noise but none will cure it.

 

[INDYMAC]

I'm not a M1 user, so I can't really comment on its lubricity. But I have found trying a different oil filter helps more than anything with start-up rattles and noises. PureOne's have been most helpful if he's looking for a place to start.

Although I haven't used it, AMSOIL Signature Series 0w30 has been reported to help with start-up noises tremendously.

Good luck.

 

[Dave Hess]

Keep using Mobil 1 since there are ZERO problems

 

[quick_16]

Originally Posted By: demarpaint
I'd like to see the whole thread. I guess there are Mobil 1 bashers everywhere.



OK this should be interesting as it's now cross posted

http://drr.infopop.cc/eve/forums/a/tpc/f/80760912/m/45510912

 

[Max_Wander]

Toyota 4 cyl has had more piston slap on M1 than any other oil. Maybe I should go back in time and tell that piston slap "its wrong! you shouldnt be happening"

 

[mechtech2]

Tell the guy with the problem to try another oil or two.
Only his individual tests mean much in his particular car.

 

[BuickGN]

Originally Posted By: INDYMAC
I'm not a M1 user, so I can't really comment on its lubricity. But I have found trying a different oil filter helps more than anything with start-up rattles and noises. PureOne's have been most helpful if he's looking for a place to start.

Although I haven't used it, AMSOIL Signature Series 0w30 has been reported to help with start-up noises tremendously.

Good luck.


That's a little different than piston slap.

 

[tig1]

Originally Posted By: quick_16
Originally Posted By: demarpaint
I'd like to see the whole thread. I guess there are Mobil 1 bashers everywhere.



OK this should be interesting as it's now cross posted

http://drr.infopop.cc/eve/forums/a/tpc/f/80760912/m/45510912





This test is a is a gimmick. This has already been discussed here at BITOG. Bench test like this are more for grease and gear oils, not engine oil.


http://www.mobiloil.com/USA-English/MotorOil/Car_Care/AskMobil/Oil_Film_Strength.aspx




You

 

[UNC017]

Piston slap is not really an engine "design flaw." Its a byproduct of using hypereutectic pistons that don't change size much as they heat and can be cold-fitted much tighter in the bore for efficiency, combined with eliminating some design features that were implemented in the 50s to QUIET engines, but which are counter to efficiency (offset piston pins and very long piston skirts).

Fortunately there is an alternative that doesn't affect efficiency so much- coating the skirts with a PTFE compound, as most manufacturers now do.

I don't think oil can possibly have much effect on piston slap noise because the source of the sound is the piston "clicking" side-to-side against the bore at TDC when its not actually moving up and down the bore. I suspect that if a different oil does make a big difference in sound, then it probably isn't piston slap that was the dominant noise in the first place

 

[demarpaint]

It could also be a noise that people are calling "piston slap", when in fact its really something else. Then changing brands or grades of oil is quieting it down, when in reality it was something else. Just a thought.

I've heard people describe sounds and noises give, it a name they read about and had no clue what the noise was.

 

[BuickGN]

Typically it's engines with forged pistons that have cold piston slap.

Forged pistons expand more when hot so cold, the clearances are looser.

 

[OVERKILL]

Originally Posted By: BuickGN
Typically it's engines with forged pistons that have cold piston slap.

Forged pistons expand more when hot so cold, the clearances are looser.


The LSx engines notorious for it use hypereutectic pistons FWIW.

The reason is that GM went from hand-fitting the pistons in the bores to bulk boring and bulk pistons. So you end up with some pistons that are, due the the inherent nature of mass manufacture, smaller than average and some bores that, due to the same reason, are larger than average. This creates noise of course. Combined with the almost complete lack of skirt on the LSx pistons and it really is a no-brainer as to why it happens.

 

[Ken2]

Terry Dyson posted here some time back that certain oils have more ability to damp engine noises. It has nothing to do with their protection of the engine, just damps more noise. I don't remember which oil brands he said damp noises more or less that others.

 

[tig1]

I think piston slap is a design flaw. I for one would not own an engine that hammered every time the engine is started cold. GM has been sued by people all over the US for this problem, and my guess is they regreit ever building them that way.

 

[PT1]

Originally Posted By: tig1
I think piston slap is a design flaw. I for one would not own an engine that hammered every time the engine is started cold. GM has been sued by people all over the US for this problem, and my guess is they regreit ever building them that way.


I have had 2 a 2002 5.3L and a 2006 6.0L...both very annoying and GM refused to do anything short of extending the warranty on the 06 to 100k which did nothing for the noise. Pennzoil 10w30 conventional did the most for noise abatement but the real fix came by getting a Toyota 4Runner after becoming thoroughly disgusted with GM forever. When you spend $100k on vehicles and the manufacturer says "they all do that" you tend to look for a manufacturer who can build an engine that doesn't knock for 5 minutes after you start it. The 6.0L got so progressively bad it would knock for 8 minutes. FWIW, you will never convince me GM cares what happens after you drive off the lot on day one as they fought my warranty claims from the beginning.