Piston Slap oil

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Aug 13, 2002
Sedalia, Mo
Alot of discussion has happened on other forums about the piston slap problem w/97-99 4.6L and 5.4L ford modular engines. One of the cures if you are OOW is using Mobil 1, has anyone had luck with this or have any other ideas???

[ October 30, 2002, 06:48 PM: Message edited by: BOBISTHEOILGUY ]
A few people I know with LS1 F-bodies have had luck reducing or eliminating piston slap problems when switching to an oil with moly such as Redline (Schaeffer oil would also work well too, and cost much less)

[ October 29, 2002, 08:10 PM: Message edited by: Patman ]
In this case it involves the '97-'99 ford modular engines 4.6L-5.4L. Engine knock for the first 10-20 seconds after a cold start-up. Ford claims there is NO damage being done, but they have replaced some engines to excessive "piston slap".I guess it is a design problem with the above listed engines.For more info go to www.f150.com, it is on their home page, bottom right column.
BR549: "One of the cures if you are OOW is using Mobil 1"

What is OOW?

I used Mobil 1 (Tri-Syn) throughout my Honda Civic's formative years and it has a severe case of piston slap. So, I don't see the stuff as any kind oif 'cure.'
However, we all pretty much agree that the new SuperSyn is a vast improvement and contains a better barrier (anti-wear) package. I still don't know if it's a cure.

As Patman stated above, the best cure known is an oil with a fair helping of molybdenum. I used Red Line which is loaded with moly with great results (80+% noise reduction) but there are other moly fortified oils like Schaeffer and Pennzoil Long Life 15W40 which cost less.

--- Bror Jace
OOW= Out of warranty
"cure" One of the should I say "bandaids" listed was trying Mobil 1 to quiet, not eliminate, the knock. I like the idea of moly
Gee, BR549, being in Missouri, you should have a Schaeffer represenative near you. Maybe contact headquarters? You might even have your pick between a few different reps.

(but how does that help us maintain this great site for free if people run off to local reps after we put in all this time and expense to help others out? please keep that in mind when looking at buying these types of products.) bobistheoilguy

I have a buddy who is into Hondas (like myself) and he complained that using Mobil 1 tri-Syn in his Civic made the noise upon start up (piston slap) even LOUDER. He couldn't believe the difference between that "premium synthetic oil" and the Valvoline Max-Life he was using (the original Max-Life formula was LOADED with moly).

So, I see the older Mobil 1 Tri-Syn as part of the problem rather than a potential cure.

It just remains to be seen whether these mass-market oils with strong traces (80ppm or less) of moly (Castrol GTX, Pennzoil, Mobil 1 SS) can actually quiet piston slap once it's already set in. I'm pretty sure that all of those will go along way in PREVENTING piston slap if you start using it early enough.

--- Bror Jace

[ October 30, 2002, 09:15 AM: Message edited by: BOBISTHEOILGUY ]
Is SEARCH a powerful tool or what??
My bad on this post, should have used the ol search function!!! You the man Molakule
Thanks to all that replied.

Originally posted by BR549:
Alot of discussion has happened on the F150.com forums about the piston slap problem w/97-99 4.6L and 5.4L ford modular engines. One of the cures if you are OOW is using Mobil 1, has anyone had luck with this or have any other ideas???

We had a 98 and a 99 4.6,still own one. Never any noise out of them with 5/30 and 10/30 Dino.Engine noise on start up can be decieving as to what it is that is making the noise.

Do these motors with problems have high miles?

[ November 01, 2002, 08:28 PM: Message edited by: dragboat ]
The piston slap issue arose in the 4.6l and 5.4l V8 engines made at the Windsor Engine Plant in '97- through somewhere in early '99. There have been isolated cases in later models, but not nearly the number that appeared early. Ford did offer engine replacement to many folks with severe piston slap issues. In many cases the replacement engine was not a new engine, but a remanufactured engine, and folks often had problems with the replacements.

Engines typically displayed Piston Slap pretty early in engine life, usually by 20,000 miles or so. If you made it past there, you were home free.

Ford continues to maintain that no engine harm is being done, and I would tend to agree. Nobody who had a slapper has reported engine failures. I own a Jeep Cherokee that has the 4.0l Inline 6 that is notorious for piston slap, but nobody ever has a problem as a result of the slap.

Various oils didn't seem to make a much of a difference in the slap.
Bror Jace
I'm curious about your Honda piston slap. I have a 1992 civic which developed the same problems about a year ago, i.e. 2-3 minutes of piston slap on cold starts. From your posts it sounds like I might be able to minimize with Redline or Schaeffer's products containing Mb. Is this slap likely to lead to other problems, e.g excessive oil consumption? And how long is a car with 109K likely to struggle along with the pistons rattling on the inside of the cylinders. Might I hope for a few more years if I treat it well? The car has been great to me. No oil consumption and still gets 39-40 mpg for mixed driving. Any thoughts appreciated. Adlumia
Guys piston slap as it has been called here can come from several things,,not willing to tackle them all in this post but will use adlumia's Honda as an example of one problem. The pistons all heat up from thermal expansion,some expand more than others depending on how they are designed. His motor suffers apparent wear in both the cylinder liner and the " cam" of the piston so now it takes longer for the knock to go away because of wear,the piston still expands but cannot expand to compensate for the wear . Moly will not cure piston knock. What it will do if plated will reduce but not eliminate further wear while knocking when cold,I do not believe that Moly plates to soft metals like pistons,the motor is going south slowly,,you can slow it down with moly plated to the cylinder walls but a higher VI oil will help more but theres a catch.These cylinder walls are lubed from the spray of oil coming out of the rod sides and probable some splash from the crank throwing oil around,,if the rod side clearance is not adequate you will get less oil spray when cold if you get the oil too thick.

I think if the cylinder walls and pistons are scored a bit" what I like about a boroscope " the Schaeffers # 132 would be a means of making a bad situation better for less money with a Dino oil like this that would not be as likely to become overbased

Molybdenum 1
Sodium 0
Magnesium 13
Zinc 1030
Potassium 1
Phosphorus 869
Calcium 1900
VIS @ 100c 12.2

or possible other oils to include Syn lubes that Molakule would be better in advising to use with the 132 Schaeffers Moly Additive than I.There is more to this 132 than just Moly as discussed previously.
Some of these motors will knock when cold and give long service after they start this but moly alone will not stop the knocking sound,,will just reduce wear from this problem.

When you see a Briggs and Stratton owners manual that says not to use a certain grade oil below a certain temperature becasue it will increase wear or damage the piston this is the splash I am talking about,,just could not insert above.

Ask Bob what the 132 Moly does for oil burners he has seen. It will help fill in the wear scuffs and stablize the rings. If it is doing that it will cushion the blow when cold without getting the VI too high in proper amounts added to the oil.
I have to believe that with the temperatures encountered in the piston/liner region, that some moly will adhere to the skirt as well as the rings and liner.
Lots of good information here. I had a '94 GM 3.1 these engines were notorious for almost anything-most of it bad (I could give a long list
) Anyway mine had piston slap when I got it (program car)When I switched to Mobil 1 10W-30 the slap did not go away and got worse over time. So much for Mobil 1 here
. Sort of agrees with someone above who indicated Mobil 1 was not the answer.
adlumia, to address your concern, I've heard of these engines lasting many tens of thousands of miles after piston slap becomes evident.

When talking to other Honda owners on Honda-Tech.com and Honda-Acura.net I've not yet heard of an engine dying due to "piston slap." Nothing like a sudden blown motor, etc ...

It's just a matter of tolerating it and Honda owners are often spoiled by refined designs and don't much care for the cacophony during start up. I had a co-worker who had a Civic like mine but a year older and around 123K miles. He figured the motor was about to go so traded it in on a Nissan Sentra but I bet he could have made it well past 150K.

--- Bror Jace
If this is indeed true re: 97-99 Modular engines made in the WIndsor plant, then it applies to Mustangs and trucks.

I can't tell you how many 99 GTs I see out on the road today and the # of 99 GT owners who have raced their stangs w/o any problems.

96-98 GTs had Romeo 4.6L SOHC V8s

The only other line that used windsor 4.6/5.4s in those years were trucks.

I have a 00 Vic w/ te 4.6 but its from the Romeo facility. I hear a slight knocking noise for the first 2-3 minutes in a cold start. It's not as loud as the piston slap from ym Chrylser 2.5L I4, but its a knocking sound.

We've attributed it to the timing chains slapping against the tensioners in the cold weather. It goes away when its warm.

I've used Pennzoil PureBase 5W-30, Quaker State synthetic 5w-30, and Mobil 1 SS 5W-30 and the noise is always there.

I drive the snot out of my engine - I hit 5300+ RPM as much as possible (I used a scan tool to log RPM) and I do plenty of forced downshifts thanks to a custom dynotune.

BUT I take very good care of the Vic: frequent oil changes and I never subject it to the torture of driving slowly and idling for long periods of time.
Yep, the '97-99 issue on the Windsor engines is the best info I can find. It was a huge issue when it appeared on the F150's of that vintage. I have no idea where all the engines from the Windsorr plant went in terms of models, but the F150's had both Romeo and Windsor engine plant 4.6l's in them. All 5.4's came from Windsor. Nobody with a Romeo 4.6 has reported piston slap - they were all Windsor engines - 4.6, 5.4, and even 6.8l V10's. Every now then there is still a scattered report, but they are very far and few in between on the new models.
Could AMSOIL 10W-30 help with the piston slap on my 02 Z28?? or should I go to M1 10W-30 or RedLine? I'm currently running M1 5W-30.
Thanks, Rick
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