A 5W50 or 15W50 provide much more resistance to shearing than either a 0W40 or 5W40. Using 0W40 or 5W40 in these hot running engine will in warmer climates, among other problems, cause premature wearing and scaring of cams, crank/journals, lifters/sleaves and other componants. This is most evident as the engine gets beyond 75,000 miles.

Contrary to what PorschePHD states, I have yet to find more than a handfull of Porsche techs (dealer or Indy) that runs the 0W40 or 5W40 in their own cars. Even many dealers south of the Mason/Dixon line fill customer's cars with the 50 weight oil. Service writers I know say the ONLY reason they use the oils on the Porsche approved list is to avoid problems with Porsche in case of engine problems.

Finally, a low COLD viscosity oil encourages seal leakage along with bleeding of the hydraulic lifters. If you want to get rid of your valve's tapping at startup, try putting in the proper viscosity oil.

If you are not interested in maintaining your engine for the long run, then run the mobil water. You'll get a little more power and a little better gas mileage. You could also drop down to the 0W20 weight oil and get even more of these things.

 

I would think that you are not running your car nearly as hard as a cup car for one.... I'm no expert. Just trying to learn...

 

Cup cars do not share the same configuration on the valve train. Our valve train relies on the oil as a hydraulic function as well as a lubrication and coolant. The cup cars are a different beast. 5-40 is approved through Porsche. I will get the list up. It was a crazy day. I am sorry for my slow response.

If your car leaks or smokes changing the weight is not the key. You have other issues that should be fixed. Normally smoking on start up is from a weak or failed turbo OR over filling. It is a dry sump system so run it a quart low. You may see the smoking stop.

99, you can preach what you would like. Please post the names of your circle, because the circle we are in is in direct with PCNA or employed by them. Not to mention, Peter is one of the top techs for Porsche in the country. He also was the first to be trained on the CGT. Between him, Bruce, Scott, Joel, Tom and Chris and myself I doubt there is a more in depth group dealing with these cars. We continue to see high mileage cars without issue and certainly have taken enough motors apart to quantify the results. I mean no disrespect, but you are incorrect and without data to back up the claims. I can post bearings, engines, cranks or anything else you wish to support the general census not just by me and the other national identities listed, but Porsche, Audi and VW. It is not a conspiracy to sell more parts, cars or other.

 

Thank you Stephen

 

Arguing about thick VS thin oil is like arguing about religion. People have firm beliefs. The general trend is towards thinner oils. 8000 RPM Hondas do well with 0w20, Corvettes and Vipers come with 30 weight. Oil analysis for wear metals does not seem to show more wear with thinner oils.

 

Hey Stephen, glad you cleared that up, the last time I had a huge arguement with 1999 regarding oil issues and I refused to get into another one!

 

Too many people do not understand how the hydraulic lifters work. Based on some of your opinions, it's amazing that the hydraulic lifter functioned at all before low multi viscocity oil was even introduced. I guess the Chevy's Mopars, etc of the 50 and 60's simply had non functional lifters since they ran a much heavier oil than some of you do. But, there is more to protection when it comes to the right weight oil. It also effects power losses through the valvetrain.

Lack of knowledge about solid lifter design and there spring tension attributes greatly to the typical misunderstanding of the function of hydraulic lifters as they relate to horsepower. Exact, precise and instant movement of the valvetrain provides the optimum power to the engine. Obviously, this is a theory and cannot be accomplished in the real world and expect the engine to last long. This was one of the purposes of increasing the spring tension on solid lifters. On hydraulic lifters, leak down of fluid is a big power robbing feature and can result in the same power loss as a weak spring.

Assume your engine's oil temperature is 240F+. Which is thinner? 40 weight or 50 weight? Which oil has beter shear protection? Since some lifters are always pressurized at engine shutdown, which of these oils will bleed down faster? Will a lifter that is not pressurized properly cause more wear or less wear? Kind of a no brainer as to which oil will better protect your engine from shearing and lose lifters.

I could write volumes on oil but as some have said, it would not matter. Some will always fall back to what is advertsed or what the manual says. For those that drive their cars moderately, it frankly does not matter what you use. For those that regularly push there cars hard to extreme temperatures, it makes a big difference.

The key is to have the right viscosity at the highest engine temperature which a 40 weight oil does not provide you like a 50 weight oil does. For those that argue for 5W40 versus 5W50. Why not the 5W50? The oil will function the same except that you gain protection at the high temp extremes. And in climates that have temperatures above 50, why not 15W50 since the flow rate of the 15 weight is the same as a 5W at these temperatures? Seems like an "ego" position rather than a technical one.

 

So for someone living in Las Vegas....you would recommend that I go to 15w50 oil (currently using 5w40)???

 

Hey 1999 it`s an engineering issue! Porsche knows what oil to use and they spec it out accordingly. Why would they spec the wrong oil--oh yeah to sell more parts. When my turbo blows up, I`m going right down to Porsche and buying a new one, that way Porsche can sell twice as many cars; a strategy
formulated on intentionally stating the WRONG oil weight in the owners manual. You can`t be serious!!!! 1999 when you build your own engine and you own chasis then you can spec your own oil weight, untill then, I think Porsche khows what they are doing. BTW didn`t they build the 917???? Un fr%@#ng believable

 

As does my lawnmower.

 

I think you are missing the point 99. We are not talking about a standard tappet. If you were pulling these motors apart you would understand why it is that poses a concern. In a cup car that is fine. The system uses an old tappet that you enter in as evidence. This is fine, but it is not the same design and your theory does not take in to consideration the rest of the active valve train. All which rely highly on the function of the oil to spin the sprockets in place.

This is not an ego presentation, ( I find great humor in that coming from you) but one based on fact and certainly the experience of pulling these motors apart. One can theorize all day, but when you see failure using something else and not when you don't the data becomes pretty clear.

 

So, as I have asked so many times before: If Porsche knows all things..then when were they wrong? When they factory filled the 996 with 15W50 and that weight was an approved one, or now when they do not approve of 15W50 in that same car. They could not have been correct both times...now could they?

 

Wouldn't it be safe to say that in fact a variety of oils can and do work? The nuance here is which "optimum" you're aiming at.........low viscosity (0-40) means less friction and a little better mileage etc. Remember the Germans are a very "green" country and one of the prime objectives being chased is fuel economy.

I could probably use 5-40 (0r 5-50) in SoCal with our warmer weather and not notice the difference.........and you can mix a quart of a different viscosity if it is needed in extremity.

But the total difference in wear to an engine like we're talking about here based upon different oil viscosities will take many miles to show up and be dependant upon driving styles, maintenance schedules, weather extremes, and the state of the engine tune.

I like the Motul brand 0-40.............

 

Hi 1999. Were the early TT`s specced with 15-50 or just the early NA 996`s? There must be a reason wht Porsche removed it from the list. I can`t believe 0-40 is just for fuel economy. I still think it is an engineering issue fot valve train lubrication. I appreciate your spirited dicussion though.

 

As recent as 7/28/2005, Porsche's "approved" list of oils included Mobil 5W50 for ALL Porsches from 1984 on.