AMSOIL European Car Formula
11-27-2007, 01:32 PM
#11
If you look at the analysis data on lots of engines, you'll see that chains hammer the oil
Believe it or not, some of the highest forces in an engine occur in the bearings of a cam chain. Chain roller bearings take some of the slack, but the stress on the oil still shows up.
The RS4 uses sleeve (not roller) bearings, which seems to be even worse.
Chain bearings are in a funky mixed lubrication regime and seem to require different antiwear additives than other components. I don't know why this is, but it's apparent from the viscosity shear and additional wear that you see in engines with cam chains. Mobil 1 typically does not perform well in engines with cam chains.
Your own personal experience with the "noisiness" of Mobil 1 tells you that something is not being lubricated well. I would contend that in engines with chains, this is the largest source of noise.
Yes, proper tension and tensioners help, but what a tensioner is compensating for is the stretch due to chain bearing wear. This has to be so. If the steel itself in a chain were to stretch permanently, it would be due to reaching it's elastic limit, which means that it is on the verge of failure.
It may actually be at startup that the largest problems occur, since at that time the entire chain is not bathed in oil. There are high pressure antiwear additives and friction modifiers that should normally coat the roller bearings or bushings. If they do not do the job, then there can be an issue.
In addition, all Audi V8's have medium to high fuel dilution. Not only is the chain bathing in oil, it is also bathing in fuel that is reacting with the metals and removing oil additive deposits.
As for overall chain life, that depends on the rate of stretch, which depends on the rate of wear. Reduce the rate of wear and you increase the life.
The RS4 uses sleeve (not roller) bearings, which seems to be even worse.
Chain bearings are in a funky mixed lubrication regime and seem to require different antiwear additives than other components. I don't know why this is, but it's apparent from the viscosity shear and additional wear that you see in engines with cam chains. Mobil 1 typically does not perform well in engines with cam chains.
Your own personal experience with the "noisiness" of Mobil 1 tells you that something is not being lubricated well. I would contend that in engines with chains, this is the largest source of noise.
Yes, proper tension and tensioners help, but what a tensioner is compensating for is the stretch due to chain bearing wear. This has to be so. If the steel itself in a chain were to stretch permanently, it would be due to reaching it's elastic limit, which means that it is on the verge of failure.
It may actually be at startup that the largest problems occur, since at that time the entire chain is not bathed in oil. There are high pressure antiwear additives and friction modifiers that should normally coat the roller bearings or bushings. If they do not do the job, then there can be an issue.
In addition, all Audi V8's have medium to high fuel dilution. Not only is the chain bathing in oil, it is also bathing in fuel that is reacting with the metals and removing oil additive deposits.
As for overall chain life, that depends on the rate of stretch, which depends on the rate of wear. Reduce the rate of wear and you increase the life.
11-27-2007, 02:15 PM
#12
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well,
sure there are stresses on the chain bearings, that's the nature of any chain.
what i'm saying is that i don't think one brand of oil over another matters in the chains themselves.
the need is for them to be properly lubricated, which is a rather simple need. chain design, materials used, shape, length, and tensioning methods is where wear will come into play, and be applicable...any type of chain.
the use of a "sleeve" type bearing is one thing. how a minutely diffrent oil affects it is just not high on the list of concerns, from a technical standpoint.
Mobil 1 being noisy most likely has to do with friction modifiers(overused?) and composition of the add pkg. which i think can affect a lot of things, but chains, i really don't think so.
the noise that may be associated with chains is probably due to their contact with mating surfaces, not the bearings or sleeves. if those are receiving sufficient amount of lubrication, they should be okay.
i think you might want to rethink the role of tensioners. they are not designed for wear related stretch so much as that a chain, with inherent play, needs to have tension properly maintained as a moving part.
what i'm saying is that i don't think one brand of oil over another matters in the chains themselves.
the need is for them to be properly lubricated, which is a rather simple need. chain design, materials used, shape, length, and tensioning methods is where wear will come into play, and be applicable...any type of chain.
the use of a "sleeve" type bearing is one thing. how a minutely diffrent oil affects it is just not high on the list of concerns, from a technical standpoint.
Mobil 1 being noisy most likely has to do with friction modifiers(overused?) and composition of the add pkg. which i think can affect a lot of things, but chains, i really don't think so.
the noise that may be associated with chains is probably due to their contact with mating surfaces, not the bearings or sleeves. if those are receiving sufficient amount of lubrication, they should be okay.
i think you might want to rethink the role of tensioners. they are not designed for wear related stretch so much as that a chain, with inherent play, needs to have tension properly maintained as a moving part.
11-27-2007, 02:39 PM
#13
Scott, have you tried an oil with a similar viscosity to the RLI?
RLI seems to be quite thick. From what I've seen, it is almost as thick as 50 wt. Thicker oil films can lead to less fuel being washed past the rings as well as less wear in general. The UOAs of RLI that I've seen on BITOG haven't been that spectacular. Not attacking you or your research, but that's what I've been seeing from other users.
Dave
Dave
11-27-2007, 03:33 PM
#16
Only the 5W40 was specifically designed to reduce dilution
Don't buy into other people's assumptions that it performs well because it is on the high 40W viscosity side. It has been adjusted to be a bit thinner for future batches. The reason for it's fuel dilution performance does not have to do with the viscosity per se, however I am not able to tell you the exact reason, due to a non-disclosure. There was some engineering done to the base oil formulation that allow it to reduce fuel wash down in the RS4 engine. There are also some VIIs and and additives that were specifically used to reduce wear in the presence of fuel in the oil.
As for it's wear performance in RS4 engines, it has shown exceptional reduction in wear, on the order of 2:1 to 4:1 reduction in Iron in particular. If you look at the data I've posted on BITOG, it is spectacular. In other engines, the results are good, but whether they are good enough to warrant switching over is entirely another matter. That's more of an economic decision.
Other variants of BioSyn have different characteristics. They do tend to endure fuel dilution much better than most other oils, however. Also, be careful with amateur interpretation of some of the BioSyn UOA's on BITOG. There is much more going on than meets the eyes. The oil has a unique chemistry, unlike other conventional and synthetic oils. There are also some problematic engines using Biosyn on BITOG with preexisting issues. One engine, a BMW X5 V8 in particular, has some problems that go back for quite a long time, including some issues introduced during service.
Finally, I cannot say much, but the oil has gone through some significant testing at at least one national laboratory, one racing team laboratory, and one very well-known and respected engine and oil testing institute, with several different viscosities having been tested. It performs as advertised. At the oil testing institute, the 5W-30 version blew away Mobil 1 5W-30 in API standard testing.
As for it's wear performance in RS4 engines, it has shown exceptional reduction in wear, on the order of 2:1 to 4:1 reduction in Iron in particular. If you look at the data I've posted on BITOG, it is spectacular. In other engines, the results are good, but whether they are good enough to warrant switching over is entirely another matter. That's more of an economic decision.
Other variants of BioSyn have different characteristics. They do tend to endure fuel dilution much better than most other oils, however. Also, be careful with amateur interpretation of some of the BioSyn UOA's on BITOG. There is much more going on than meets the eyes. The oil has a unique chemistry, unlike other conventional and synthetic oils. There are also some problematic engines using Biosyn on BITOG with preexisting issues. One engine, a BMW X5 V8 in particular, has some problems that go back for quite a long time, including some issues introduced during service.
Finally, I cannot say much, but the oil has gone through some significant testing at at least one national laboratory, one racing team laboratory, and one very well-known and respected engine and oil testing institute, with several different viscosities having been tested. It performs as advertised. At the oil testing institute, the 5W-30 version blew away Mobil 1 5W-30 in API standard testing.
11-27-2007, 04:35 PM
#19
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Re: why are you looking?
I'm planning to keep this car for the long haul and prefer to give it the best oil available. I also happen to live near where AMSOIL is blended, so it is locally available. Based on RIRS4s compendium of oil analyses and other anecdotal information, I'm inclined to switch from Mobil 1 forthwith. The car has clocked 7600 miles thus far with nary a squawk.
