[Anthony]

D. Comments about Synthetics

The single advantage of synthetic is it's ability to operate at temps above 305 F without oxidizing rapidly. Since there are few applications where the oil gets that hot the advantage is moot and contributes zero to extended drain capability. Even my CBX with a partial fairing blocking part of the engine never gets the oil to 300 even running on the freeway at 80 in summer weather...I've checked. People tend to think that I hate synthetics since I usually try to point out that they to not necessarily allow longer change intervals (which is the most often quoted reason for using them seems like to justify the price). They are actually excellent products and do offer some other slight advantages in some situations. It is argued that the film strength is better with a synthetic and that the dynamic viscosity characteristics are better....along with the previously mentioned reduced oxidation rate above 305 F oil temp.

The question is, will the engine actually take advantage of those characteristics or ever be operated in a regime that requires synthetic or that would make synthetic advantageous??

Yea, I agree, oil in turbocharged applications is a good candidate for synthetic.

A synthetic will typically be a slightly lighter weight base oil due to the flatter viscosity curve as the temperature of the oil changes. Thinner oil will always be better for fuel economy (within reason....as long as it is not so thin that metal to metal contact occurs due to lower film thickness) which is why manufacturer's specs went from 10W30 to 5W30 and to 0W30 in some applications.

Synthetic products are excellent products for the most part but you just have to understand where they excell (very high and very low temperatures) so as to judge if they are justifiable in your case. You aren't every going to HURT anything with synthetic....you just might be paying a lot and expecting a lot more than you are actually getting, that is all.

First, though, let me be clear. Synthetics, such as Mobil 1, are excellent products. They can survive at temperatures well above the oxidation limits of conventional oil of 305 F. If an engine operates at those oil temperatures then synthetic is applicable. Synthetic offers good low temperature viscosity and pour points...low meaning below -40. Down to the -30/-40 range conventional oils are fine. If you are searching for oil on the northslope and cold start regularly at -40 then consider synthetic. Other than that, synthetic oil's usefulness is questionable in passenger cars.

Racing teams use synthetic oil for several reasons. First and foremost is marketing. If it is "good for racing" then it must be great stuff, right??? Fooled you , didn't it..!!! LOL LOL The racing teams get paid lots of sponsorship $$$$ to run the oils and put the stickers on the cars. That is why they use it. If someone paid them enough money to run lard in the motors they probably would. The engines will run fine with conventional oils as evidenced by teams sponsored by conventional oil companies that do not run synthetic.

In racing things happen to often drive the oil temps above 305 F. If this happens....the synthetic can take it and conventional oil would have a limited life. It lets the NASCAR boys tape over the oil cooler for better aero during qualifying and if the oil creeps to 350 in the process there is no harm done. So it has a marginal use and is a good insurance policy for when the going gets rough and that fender gets pushed in an blocks off the oil cooler.

If you are using synthetic oil, what gain or advantage do you expect...??? I understand the idea of putting the "best" into something and if you want to use synthetic I have absolutely no problem with it....just don't expect miracles and realize that the likely hood of really exploiting the advantages of the synthetic product in a street engine is pretty slim.

The proper application of synthetic lube products (in things like the VI package in conventional oil) is already being used and in the bottle of every oil you buy so the chemists that really understand the advantage of synthetic products are putting it in the correct applications for you.

I have an air cooled backup generator for our house that we need occasionally....it gets 20W50 Mobil 1 because it will run so hot on summer days when needed. Good place for synthetic and utilizes the advantages of it.

In very cold weather, there is less viscosity increase with synthetic. It will improve cranking speeds. Is it needed to help the engine down to -40....no....but it will make them easier to crank over.

Like I said, I am not in any way running down synthetics...just want to make sure no one thinks that there are huge advantages to them unless they are operating the engine in a regime that forces the oil to very high or very low temperatures. The main thing that I always hate is the belief that synthetics allow much longer change intervals....a belief kept alive by Amsoil and their BS.

BTW...you allude to synthetics and better oil consumption and better adherence to parts...??? My observations and experience are just the opposite. Synthetics seem worse for these features. Primarily due to the lower viscosity of the base stock, I suspect.

If you doubt this, pour synthetic in a drain pan, let it set and then tip it up on edge to drain. Do the same with an equal weight conventional oil. After several days the pan is going to be drier with synthetic..... Most of the people that I talk to with Northstar engines, which have a tendency to use a little more oil than some other engines, find that the engine uses even more with synthetic. I find that if I can convince them to use conventional oil and run the snot out of the engine occasionally the oil economy improves considerably. Try comparisons with the different oils and see if it affects the economy.

E. Some New Vehicles Specify Synthetic Oil

There are a number of new cars that specify Mobil 1. I work specifically on several of them. The Corvette LS1 is specified a synthetic oil engine and the RWD Northstar engines in the SRX/STS/XLR are also factory filled with Mobil 1. So will be the supercharged Northstar in the STS-V/XLR-V. Why you ask?? One simple reason. There is no need to put an oil cooler on the car if it has synthetic oil in it. If the owner takes it to a track day and runs the car on the track hard the oil will get over 305 without an oil cooler. Synthetic oil will take it and conventional oil would be questionable. Otherwise, the performance cars like this would all need large oil coolers and all the associated plumbing. Putting all that extra equipment on all cars so that the 2% that actually see the track will keep the oil cool is not a good idea. Better to leave off the cooler (less expense, less chance of oil leaks, less complexity, less to maintain with age) and protect the small percentage of engines that might get the oil above 305 with the synthetic. Regardless of what you have read, were told or believe this is the main reason that factory cars are spec'd for synthetic. Period. I know because I work with them everyday and can assure you that that is the truth.

Interestingly, the real hotrods, like the STS-V run oil coolers AND synthetics because the engine will push the oil temp over 305 even with a large cooler if used for continuous track work. So, even though the car has an oil cooler, the same logic and reasoning applies...use the synthetic to keep from having to put a HUGE oil cooler on it.

The engine oil temp does not run any cooler with the synthetic, by the way. I have run lots of engine cooling tests with conventional and synthetic oils and the oil temp is the same regardless...just that the synthetic has higher oxidation temps.

If an engine is designated for factory fill with synthetic it has other uses as well. In the case of the Northstar engines in the STS/SRX/XLR the engine has variable valve/cam timing (VVT) on all four cams. The VVT system uses engine oil pressure as a hydraulic system to move the cam phasers using control signals from the PCM. The VVT system is a hydraulic circuit that is separate from the normal engine lube circuits. In cold start situations the viscosity of the "hydraulic oil" must reach a certain level before the VVT system will respond quickly enough to allow it to be used. The more linear cold viscosity of the synthetic products allow earlier application of the VVT on cold starts. Without the synthetic the system would still work fine...just the cam phasers would "park" until the engine oil reache a certain temperature. Since the synthetic was spec'd anyway, it is exploited in the engine design to be able to better utilize the VVT system.

So.....that is why factory cars have synthetic. Not because it is magic or has better "wear" properties...just because it can live above 305 for extended periods of time. Interestingly, the synthetic only adds about 25 degrees of increased oil temp range above 305. The metal parts in the engine, that are much hotter than the oil and that are cooled by the oil, cannot take much higher temperatures. Aluminum starts to loose strength and gets "soft" enough that it will start to collapse in structural areas. Even hardened steel , like tappet faces, start to temper and soften at temps approaching 375/400F so if the oil is starting to approach 330 or so the tappet faces are getting close to the range that they will be starting to temper and anneal. Not desirable. In a race engine that will be torn down after the race and wear parts replaced this is not such a stringent condition but in a passenger car or street bike engine those temps cannot be seen without damage.....so.....the high temp capability of the synthetic oil cannot really be exploited by much.