innovator

I have to say, that one big disappointment I have with my newly acquired 10,000 mile 996 turbo, has been the infamous engine rattle that is deemed normal by those in the know. I absolutley love the car, but I never had a car that sounded like it had a bad timing chain. I have been a European car tech for many years, and while I have never owned a Porsche before, I have worked on many, and pretty much everything else the Germans have to offer.. That being said, I never realized before ownership of the 996 turbo, just how freaking annoying that rattle is. Honestly, I could not live with it, and they all seem to sound this way.

For piece of mind, over the last week, I started a thread here, as many others have, to gain some perspective. I have listened to 7 996 turbos the last week, and they all made this same noise from the same place (under the timing cover), so I am convinced it is typical and there is no need to worry excessively as I did. I've heard many variations from various Porsche techs, on the cause of this rattle.. Some say oil pump drive, chain tensioner, thrust bearing, balance shaft gear lash.. I am not 100 percent sure there is a true lasting mechanical fix for it. I mean, you gotta know what causing it to fix it right? That is, assuming there is anything wrong to begin with, which there is probably not.. The rattle is acceptable to Porsche, and deemed 'normal' , so I figured I would just have to deal with it.


I'll be honest with you gentlemen, I couldn't live with a 1980 Subaru sounding, 996 turbo. I read and read, and I saw where some people have had some luck using Delvac or Rotella. I have used Rotella before in high HP turbos, but there was never any magic to it. I must admit, I scoffed at the idea of it helping the rattle. I had already tried several other higher viscosity oils with no love.. Amsoil, Royal Purple, Syntec 5w-50. None of them made a damn bit of difference. I was ready to tear the engine down and get to the bottom of it...

So today, I was starring at a 55 gallon drum of Rotella 5w40 T6 that we use for fleet trucks. So I figured, what the hell? Being cautiously pessimistic, so as not to disappoint myself, I drained the engine, and filled it with Rotella. I wasn't expecting any miracles.

Shock and awe. No exaggeration. I was dismissive of others who claimed it reduced the rattle, attributing it to auto suggestion, but man, I was wrong to do that! I cannot believe the difference it has made. The hot oil pressure is exactly the same as it was with 5w50, yet the rattle is barely noticeable, unless you are right on top of it. I took the car for several WOT romps, still no intolerable rattle, as it was before with freshly changed oils. Don't get me wrong, you can still hear it, but I think I can live with it at this level. It has to be something in the additive package, because on paper, this oil is not thicker by any substantial margin that should yield this kind of result. My thought, is that the perhaps the chain tensioners are better able to keep the chain more taught at lower RPM with this oil due to a more stable viscosity which, takes some lash/play out of the timing components that are the root of the rattling . There is no other logical explanation. Bottom line, overall, the engine sounds much, much better!! I hope it lasts...

I don't know if Delvac ESP would work any better, but I pay 3.50 a quart for Rotella, and it's my new best friend..

Kevin

Wow a happy "synthetic" diesel oil customer.. But.. It's not Porsche approved.. It for your MACK truck..

Good for you. API rated. I swing towards the Mobil Turbo Diesel Truck, and Mobil Delvac. The metal conditioner package in these oils are for sure working with the gears and chains. Cheers

SSST

First you can't hear it at WOT. Second, it's part of the charm of owning a Porsche. Third, I swithched to the M1 TDT 5-40 and now it doesn't rattle.

innovator

Did you try Rotella T6 or just TDT? I will order a case of TDT for the next time I change it to compare.

Yea, the WOT is priceless, but I always seem to catch the light

innovator

I never figured it would work..

SSST

Just the TDT at Kevin's recommendation. I can see where the Rotella would do the same thing. I used to have an F350 TD and ran Rotella in it. An F350 TD pulling a 13K lb trailer through Raton pass in July is a lot tougher on an oil that a street driven Porsche.

Dock

The minor engine rattle at idle doesn't bother me one bit.

Besides, the minor engine noise PALES in comparison to the noise I get from my LWFW when I'm sitting around idling in neutral with the clutch released.

haulinkraut

I am running the rotella T6 right now too. So far I get higher oil pressure than with Mobile 1 TDT 5w40. Also I noticed on the Mobile 1 that even the TDT seems to lower the rattle but comes back quickly. Most likely due to the oil breaking down. The Rotella is now at 1500 miles and sounds the same as the day I changed it. We'll see how it does.

PAULUNM

Another point of reference- my IMS noise started to come back after 1k miles on the M1 TDT.

Currently running Delvac 1 with about 2500 miles on it, and the noise is just barely starting to come back- which means to me the Delvac 1 is less prone to shearing.

I do hear great things about T6- and it's a lot easier to find than Delvac 1 (which by the way I recently learned you can buy at most United Truck locations).

jpflip

I have to admit that Kevin finally convince me. I am running TDT since about 600 kms. On the first start nothing really seems different. Strangely it quiet down after several kilometers. But I prefer to do a couple more thousand kilometers before I celebrate the disappearance of the growling.... With the Castrol Syntec, it came back after about 800 kilometers.... Fingers crossed....

LVDell

That noise doesn't bother me at all. It's relatively minor in terms of sound. It sounds (no pun intended) like the TDT oils are just masking the sound rather than solve the problem?

I have one of John's speedtech free flowing exhausts with cat bypass so I really don't hear much anyway

nick49

The "death rattle" went away with Mobile 1 TD 5w40. Good stuff! haven't even noticed a hint of noise since.

Kevinmacd

Think it's only temporary as the oil gets used more. I noticed the reduction in sound at every new change out, but put about 2K mile on the change it will be there again!

Macster

Exactly.

That the noise comes back so quickly highlights just how quickly these supposedly so superior diesel engine oils break down when subjected to the demands the 996 Turbo engine places on its oil.

To make matters worse to gain the temporary peace and quiet the whole of the engine is running this oil.

What perfectly good internal engine oil/bearing interfaces are being sacrificed to quiet down what can only be an abnormal noise?

The noise must be an abnormal noise based on the lengths some owners will go to in a effort to quiet the noise.

An abnormal noise then that almost certainly arises from some mechanical problem -- that may not be that expensive to fix if dealt with early/soon.

A mechanical problem that almost certainly will not get any better over time and in fact will almost certainly get worse, to the point these currently highly favored diesel engine oils can no longer deliver the level of quiet some owners seek.

When that time comes, well, there's always 75w-90 transmission oil. But not a Porsche approved 75w-90 transmission oil. Oh no. Be sure to use a transmission oil approved for diesel truck transmissions.

Sincerely,

Macster.

Dock

The next thing you know some people will be changing their oil every 2,000 miles (or maybe even more often).