Recommended Synthetic Oil for 1985 Porsche 911

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Hoping you oil folks can help. My 1985 911 3.2 litre originally used dino 20W-50 oil. Porsche has approved Mobil 0W-40 for all cars back to late 70's. Now I'm hearing Mobil 1 15w-50 might be the better choice. Also hearing Mobil may not have enough zinc and phosphorous for proper lubrication in my high reving flat six engine. Is zinc and phosphorous that critical? Would synthetic 15w-50 be the preferred choice over 0w-40 - if yes, why would Porsche have recommended 0w-40.
 
I think Mobil answers the question pretty well themselves, here is the same question and a response from their website:

Does Mobil 1 Contain the Additive for Flat Tappet Cams?
I build a few engines a year as I do muscle car repairs and I have been having a lot of camshaft failures. I just read that it is because the oil no longer has the additive for flat tappet cams. Can I use Mobil 1 to break in fresh rebuilt engines of '60s and '70s tech? Is it too slippery for new ring break-in? Will it give protection on new cam and lifters?

For older, flat tappet engines where wear may be more of a concern, we offer a number of oil products which are higher in phosphorus than API SM/ILSAC GF-4 oils. These include Mobil 1 15W-50, Mobil 1 Extended Performance 15W-50 (1200 ppm phosphorus), Mobil 1 0W-40 (1,000 ppm) and Mobil 1 High Mileage 10W-30 and 10W-40 (1000 ppm). For all newer engines and flat tappet engines in normal service, API SM/ISLAC GF-4 oils are preferred for better fuel economy and for the protection of catalytic systems with lower phosphorous (800 ppm).
 
I have a 1989 3.2 Carrera. Currently using Brad Penn 20W-50 per suggestion of a few people who know their oil and older air cooled Porsche's.

The current 15W-50 M1 does not have proper levels of ZDDP for our air cooled Porsche's. Let alone the 0W-40, I would not use either.
 
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Hoping you oil folks can help. My 1985 911 3.2 litre originally used dino 20W-50 oil. Porsche has approved Mobil 0W-40 for all cars back to late 70's. Now I'm hearing Mobil 1 15w-50 might be the better choice. Also hearing Mobil may not have enough zinc and phosphorous for proper lubrication in my high reving flat six engine. Is zinc and phosphorous that critical? Would synthetic 15w-50 be the preferred choice over 0w-40 - if yes, why would Porsche have recommended 0w-40.




Why not use a high zinc synthetic 20W-50?

Amsoil 20W-50 TRO

http://www.amsoil.com/dealer/techservicesbulletin/TSB_Flat_Tappet.pdf
 
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The current 15W-50 M1 does not have proper levels of ZDDP for our air cooled Porsche's. Let alone the 0W-40, I would not use either.




According to Mobil the 15w-50 has 1200ppm of phosphorus, the same as the Amsoil high zinc oils.
 
ZDDP (Zinc-Dialkyl-Dithio-Phosphate) is a synthesized molecule containing the elements Zinc (Zn), Phosphorus (P) and hydrocarbons. This molecule has the ability to easily dissolve in lubricants and oils and is ideally suited as an anti-wear agent for metal-metal engine surfaces.

It is important to note that the wear protection properties are due only to the characteristics of the ZDDP molecule and not to Zn or P in the oil in other forms or from other sources.

This means that if a particular motor oil mentions the addition of Zn alone, or P alone, the ZDDP molecule is _not_ present in that motor oil. Also, it is possible to measure a level of Zn, and a level of P, in a motor oil and still not have any ZDDP. The ratios of Zn and P can be manipulated by simply adding Zinc salts or phosphates, but again this does not produce ZDDP and has no anti-wearing action. Last, depleted ZDDP releases Zn and P into the motor oil and testing for levels of the pure elements is not a gauge of the status of the ZDDP level.

What does this mean? If you see an oil additive or a motor oil listing only a level of Zn without a level of P, then there is no ZDDP in that product.
 
David, Impressive first post. Do you have a source you can cite for that information? Interestingly Amsoil is listing phosphorus and zing, but not ZDDP.
 
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David, Impressive first post. Do you have a source you can cite for that information? Interestingly Amsoil is listing phosphorus and zing, but not ZDDP.




What does this mean? If you see an oil additive or a motor oil listing only a level of Zn without a level of P, then there is no ZDDP in that product.
 
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ZDDP (Zinc-Dialkyl-Dithio-Phosphate) is a synthesized molecule containing the elements Zinc (Zn), Phosphorus (P) and hydrocarbons. This molecule has the ability to easily dissolve in lubricants and oils and is ideally suited as an anti-wear agent for metal-metal engine surfaces.




True enough. But there are more than a single form of Zn, P oil compound used in lubricants.

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It is important to note that the wear protection properties are due only to the characteristics of the ZDDP molecule and not to Zn or P in the oil in other forms or from other sources.




Not exactly true. Please cite a source, as requested.
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This means that if a particular motor oil mentions the addition of Zn alone, or P alone, the ZDDP molecule is _not_ present in that motor oil.




You are: "A physicist by education, David taught physics at the University of the Pacific in Stockton, CA."? Well what you wrote is very faulty reasoning. Any given could oil contain ZDDP and the company could only could mention, write or otherwise only ever publicly talk about Zn (or P).....and this would NOT be proof of no ZDDP.

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Also, it is possible to measure a level of Zn, and a level of P, in a motor oil and still not have any ZDDP. The ratios of Zn and P can be manipulated by simply adding Zinc salts or phosphates, but again this does not produce ZDDP and has no anti-wearing action.




So you have proof of this? Which oil company? These would be some high wear oils.

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Last, depleted ZDDP releases Zn and P into the motor oil and testing for levels of the pure elements is not a gauge of the status of the ZDDP level.




True enough to some extent. But would we not see elevated wear metals in such samples.

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What does this mean? If you see an oil additive or a motor oil listing only a level of Zn without a level of P, then there is no ZDDP in that product.




WHAT a bunch of huey!!!!! Very poor reasoning from an engineer.
 
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David, Impressive first post. Do you have a source you can cite for that information? Interestingly Amsoil is listing phosphorus and zing, but not ZDDP.




This is not true. Read the second sentence:

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Engine oils contain anti-wear additives and the most com-mon anti-wear chemistry is zinc dialkyldithiophosphate (ZnDDP), which contains a combination of zinc and phosphorus.




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Sometimes I just have to laugh! A fellow makes a first post, written in "reasonable scientific language" and it's suddenly the truth. Challenge, people, challenge!
 
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David, Impressive first post. Do you have a source you can cite for that information? Interestingly Amsoil is listing phosphorus and zing, but not ZDDP.




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Sometimes I just have to laugh! A fellow makes a first post, written in "reasonable scientific language" and it's suddenly the truth. Challenge, people, challenge!




I never passed judgment on the truth of his statements, I asked him to provide a citation for his information.
 
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I never passed judgment on the truth of his statements, I asked him to provide a citation for his information.




Sorry I wasn't talking to you in particular - sorry my reply was to you - it should have been to jorton . More of a general statement, though.
 
I talked with a vintage Porsche racer at the North Island, San Diego meet that races a couple of valuable cars, an RSK and a 911 RS. He said that he switched to Red Line and with a couple of friends had a 55 gallon drum of special 20w-50 mixed up. RLI will also mix up a special batch of oil for you in batches as small as 5 gallons. You can talk to the formulator, Bill and talk over your situation with someone that can give you very specific answers. You can then follow all this up with some help from Dyson Analysis. This kind of approach will get you better information and a better oil in your crankcase. Could be fun, too, at least for a gear-head.
 
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If you see an oil additive or a motor oil listing only a level of Zn without a level of P, then there is no ZDDP in that product.





Non sequitur, Dave.

Your proof is through the absence of information.

By the same logic, McDonald’s doesn’t have ketchup because it’s not on the menu.

Oh, big supersize welcome to the forum too.
 
Hello, and thanks for the welcome!

Sorry for that imprecise sentence, what I meant was:
If you see an oil additive or a motor oil listing only a certain level of Zn with zero P, or a certain level of P with zero Zn, there is no ZDDP in that product.

It is (as I can tell you are aware) a fixed attribute of the ZDDP molecule to have 1 Zn, 2 P, and 4 S atoms in each molecule with varying molecular weight alchohols attached to them.

The whole point of the statement was to point out that if there is ZDDP in a product, by molecuclar definition there will be BOTH Zn and P. The atomic mass ratios of the two in a pure ZDDP molecule are 1.06 Zn to 1.00 P, but in the manufacture of ZDDP, it is often overloaded with Zinc Oxide in order to augment the anti-corrosive characteristics. This results in a ZDDP "package" with a Zn to P ratio greater than 1.06 to 1.00.

Mixes of additives in oils are proprietary, but some educated guesses can be made as to the contents by doing atomic spectroscopy to get mass ratios, and FTIR (Fourier Transform Infra Red) Absorbance to infer molecular makeup. Interpreting an FTIR is a learned skill, since the absorbance of complex molecules in a substance such as oil can overlay each other.

Some of the newest oils, such as those from Mobil 1 and Valvoline contain approximately 0.08% Zn and <.001% P (below testing limits). In these formulations, the Zn contribution cannot be from ZDDP. Nevertheless, since Zinc Oxide is a proven anti-corrosive constituent of ZDDP, it is easy to conclude that an oil manufacturer would use Zinc Oxide by itself to help boost the acid neutralization capabilities of oil. Since it has been employed in this capacity in oil formulations for many years, it's use instead of a newer compound may help avoid extensive retesting by the API in order to claim an API certification.
 
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That makes sense. We have not seen these (essentially) zero ppm P oils show up yet.




We were surprised as well to get the test reports. Being classic car enthusiasts, we are concerned enough to have Harris Laboratories in Houston, TX perform the ASTM standard D-4951 test for Phosphorus. They are one of the largest and well respected labs in the US for petroleum testing, with a particular expertise in oil and additives. When we can, we will post the reports themselves.

The Valvoline was the 10w30 Premium Conventional Oil, and the Mobil 1 was the Extended Performance 10w-30 Fully Synthetic Oil, both claiming to exceed the API SM spec.

The API SM spec for the following oils:

SAE 0W-20, SAE 5W-20, SAE 0W-30, SAE 5W-30, and SAE 10W-30:
max P of 0.08% and min P of 0.06%.

for all other formulations:
no maximum limit, but the min is still 0.06%

The Phosphorus spec is classified as a non-critical spec under ASTM D 3244.

If the EP anti-wear package is based on a different technology such as Boron, then it may explain the total absence of Phosphorus in the oil. If an oil passes all test sequences applicable to the rating, then the actual additive package used is not an issue. Indeed, both Mobil 1 and Valvoline (among many others) have begun putting Boron in some of their formulas.

Unfortunately for those of us who own older cars, Boron is as yet unproven as an EP lubricant in the flat tappet cam/lifter interface. Of course for more modern engines, I doubt there will be any problems. It is unlike a large company such as Mobil or Valvoline to open themselves up to liability on a whim. I can state with equal certainty that they do not consider the liability of older cars being damaged large enough to worry about.

If your car was manufactured before 1988, the engine was designed to operate correctly using SF oils, which had relatively large concentrations of ZDDP, and the flat lifter camshafts and lifter feet were usually heavily phosphated at the time of manufacture to ensure correct break-in.

As far as oil company liability, if someone sustains damage to an older engine while using SM oil as many have, I believe that the oil company's lawyers could make a compelling case that the individual was supposed to have looked in the owner's manual to discover what the appropriate oil spec was for that vehicle. Once again, it is up to the individual to gather the information and make their own informed decisions.

Sorry to go on so long, but this issue has become critical for us old car guys.
 
David,

Have you evaluated any of the Mobil 1 oils I posted that Mobil specifically claims have extra phosphorus to be compatible with flat tappet cam engines? According to Mobil, these are:

1) Mobil 1 10w-30 high mileage,
2) Mobil 1 10w-40 high mileage,
3) Mobil 1 0w-40, and
4) Mobil 1 15w-50.
 
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Boron is as yet unproven as an EP lubricant in the flat tappet cam/lifter interface.




Mobil 1 has been using boron for quite some time. If you go to the VOA section you'll see that from about 2002 or 2003 onward, they were using about 260ppm of boron. Amsoil is using a good dose of boron in their 5w-30 and 10w-30 oils. Their have been studies done (one is on this site somewhere) that showed boron + lower levels of ZDDP are actually a better anti-wear package than high zddp alone. They work in a synergistic fashion.
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Molekule has a good write up on boron.

Boron Link
 
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