Run the M1 Turbo Diesel Truck vs 0W40.

If you can get the 5W50 run it.

Forget the name on the bottle, the importance is making the switch vs waiting!

And yes, like Hoosier Daddy just mentioned, the 5W40 is getting bulk delivered into car dealerships.

 

FYI- I noticed over the weekend that Autozone now carries M1 5w40 turbo diesel oil. $7.99 a quart.

 

Never mix oils unless you know, FOR A FACT, that the stabilizer chemistries are identical. Even between one Mobil 1 weight and another you can have differences...

 

I see where the question about intermediate shaft noise quickly turned into another oil session. Since the only 'death rattle-like' noise my car makes is under low-speed acceleration during that instant I realize I would have prefered the next lower gear, I guess I don't have IMS noise. Otherwise my baby is as quiet as one of these engines gets.

On oil, specifically Mobil 1: I've just been telling the Dealer "use Mobil 1" (This after he told me they had something cheaper). I guess I'll have to assure myself the Mobil 1 they're using is the 5-50W. I track my car three times a year and put 6,500 miles a year on the odometer. I have the oil changed each year, so that's my interval. So far (2.5 years of ownership), I've never had to top up. On the same schedule I added oil twice between changes on my normally aspirated 993.

 

quite a few of the MBZ amg guys have changed from 0W40 to 5W40, I shall..

 

My original question still is unanswered. I asked if there was any indication that the valve guides in the 996 turbo engine exhibit the same "weakness" the 993 engine has. These valve guides in the 993 get out of round and start to leak oil.

One independent Porsche shop in my area even suggested that the weak valve guides in the 993 engine were "deliberately designed that way" as a sort of long term maintenance item. (similar to, for example, having your fuel injectors cleaned outside the engine on a flow bench - every 100,000 miles or so).

Thanks for your replies

 

From the lil time I've spent on here, it doesn't seem like the 996TT valve guides are prone to premature wear as in the 993's, I think. I don't see a lot of topends or burning oil topics....

 

porschemikeandnancy
I have never heard or seen a 996TT or any modern GT1 derived engine having valve guide issues..

 

I was told by my Porsche Service Shop that using engine oil designed for Diesel's is NOT a good idea. Made for lower RPM engines and has (abrasives) CORRECTION: detergents and other additives to deal with unique characteristics of Diesels. His advice is any good quality synthetic (He is still using Mobile 1) but replace one quart with Redline (to get said benefits of proper additives - ZDDP).

Cut the filter and look for tell-tale sign of problems on every oil change (like IMS and RMS) before they happen.

He has customers with hundreds of thousands of miles on their cars collectively, from 944's to 911 TT. Daily Drivers to Track Day cars (Race only cars get pure Redline). This has been proven to be a reliable mix.

 

You really think they put abrasives in diesel oil? Not a chance.

Diesel oil has better wear ingredients (ZDDP), LOTS of people use diesel oil in their gasoline motors.

 

I would NOT assume your dealer is using 5w50- I would put money on it that they are using 0w40.

 

My pre-purchase research turned up no valve guide wear issues with the Turbo engine. (I have just over 236K miles on my 02 Boxster's engine and valve guide wear is not yet surfaced, as best I can tell by the lack of engine noise and still quite low oil consumption.)

However, as always I must stress the above assumes reasonable servicing intervals. My 02 Boxster has received 5K mile oil/filter services for its entire service life. The valve guides (or worse) might very well have given up the ghost before now had I instead changed the oil every 15K miles as the owners manual stated.

The "weakness" of the 993 valve guides is primarily due to the air-cooled nature of the engine and the fact the valve guides run hotter. Heat soak tends to break down the oil so upon next startup wear can ensue. Over time...

Plus you have to consider what the heat does to the valve guide seals. Leaking seals can mimic at least the smoking and oil consumption symptoms that worn valve guides produce.

It doesn't help -- if my info is correct -- that the valve guide material was not as good as it could have been. But this was not a deliberate act of sabotage on Porsche's part. More likely a cost decision. Harder, or better wearing guides are more expensive and the softer guides were assumed to be good enough.

Porsche is not alone in this regard. 'way back in the early 70's when I dabbled in engine rebuilding one of the first things I was taught when rebuilding an overhead cam engine was to replace the factory valve guides with a quality aftermarket guide.

Much better material though the guides were more costly. However, not excessively so. The added cost was just a tiny fraction of the total cost to rebuild. But for a company making thousands and thousands of engines a dollar here a dollar there makes for a significant savings.

Sincerely,

Macster.

 

I was told that while diesel oil was a superior oil for diesel engines it was not recommended for gas engines.

Primarily the concern is because diesel engines generate a lot of soot and a lot of this soot makes its way into the oil and along with the water in the oil and because diesel engines run cooler this oil with high levels of soot and water can produce sludge.

To counter this diesel engine oil is very high detergent to help keep the soot suspended in the oil instead of letting it settle out.

But this high detergency can result in foaming of the oil. However, because diesel engines have a lower max. operating rpm than comparable gas engiens and because the oil runs cooler and the diesel engine's oil system is designed to deal with the possibility of foaming this is not a problem.

However, gas engines collect of course gas vs. diesel fuel, water, and lower levels of soot. And gas engines and their oil run hotter and of course gas engines turn more rpms, at least when being pushed.

Thus with diesel oil higher levels of foaming may result with the risk some aerated oil being fed to the engine's bearings (or valves) under high speed high heat and with oil that has accumulated some miles. Some dyno testing has found even gas engines on gas engine oil aerate their oil enough that oil being fed to the lifters contains enough air to cause the lifters to collapse a bit at higher speeds and the valve action is affected enough hp falls off at higher rpms until a better oiling system is fitted.

While one can run any oil he choses I believe in using diesel oils in diesel engines and gas oils in gas engines.

Sincerely,

Macster.

 

In the end it's your engine. You will have to make your decision. However, I have tech data sheets from Mobil/Exxon engineers that give the green light to run Turbo Diesel Truck oil in GAS engines!

Cannon, your mechanic has some flawed reasoning there. You do more harm by mixing the Redline with your Mobil 1..

 

Kevin, do share for the greater good.

I do not claim to be an expert...but using 1 qt of Redline to add ZDDP to Mobil 1 does not seem harmful. Seems to me the recommendations are for the same reason people recommend Diesel Engine Oil in a Gasoline Engine.

From a layman's perspective, using an oil designed for one type of engine in another seems counter intuitive, however using a racing oil in a street car does not. Sorry if the chemistry is not so obvious as to what may be so bad with this mix.

This topic has peeked my curiosity and I have been doing some reading...seems to be a common question. What I can gather in the last few minutes is that some companies do not recommend, others are good with it - as long as the Diesel oil is Dual rated and has similar viscosity rating as the recommended gas engine oil. There are more detergents to deal with the dirtier aspects of a diesel engine and the greater miles expected of it. But they also seem to warn of too much of a good thing - too thick and too much detergents effecting the Cats.

Here are some tidbits:
Amsoil is OK with it: http://www.amsoil.com/storefront/hdd.aspx

From Castrol:
A gasoline engine oil is formulated differently to a HDD (heavy duty diesel) oil, the main reason for this is the need to handle the combustion by products that are created (diesel is dirtier than gasoline). If you were to use a gasoline oil in a heavy duty truck you could expect to see high levels of sludge, wear and eventual engine problems; however using the other way around can have advantages. Sludge protection and deposit control on HD lubricants are strong as well as wear protection. On most high performance engine lubricants you will see that they have both diesel (API C) and gasoline (API S) performance.

So my conclusion is - Diesel Oil is OK - as long as it is the right one. Not just any and every Diesel Engine oil will do. Be careful on your selection and as Kevin points out - you will be good to go. I would certainly want to use a proven brand and weight as to not play the guessing game.