Amsoil

[MChalkley]

JBM - Great info! Thanks for checking on that. I may start minimizing the inventory a little myself. I knew that the diesel standards are more stringent, but I've been more of a stickler for viscosity specs than you were told you need to be. It works for me. I trust them. I think PaulB does, too. He had very good things to say about them in one of his posts. /w3tcompact/icons/smile.gif

Mark

 

[Anonymous Poster]

I took a 3-day power transmission class a couple of weeks ago. One of the subjects of the class was lubricants. The unit of measure for viscosity is the time in seconds required for 60 ml of oil to flow through a standard orifice at a standard falling head (pressure) and at a given temperature. Viscosity is measured at both 212F and at 100F. The units are Saybolt Universal Seconds or SUS (sometimes called SSU).

We learned the single most important property to match when choosing oil is viscosity. One thing that was very interesting is that the allowable spec for example a 10W rating is so large that the SUS number can vary 20% or more and still meet spec. The instructor said this large range was originally adopted by SAE to keep the oil prices low in the hope that people would change their oil more often.

The spec range is similarly large for each oil weight. This means that if you were to choose oil with a weight different than the weight specified for your machine and that oil is towards the far end of the spec, then the viscosity could be significantly different than what is specified for the machine.

For example from a chart I am looking at, 10W ranges from 115 to 170 and 15W ranges from 185 to 350 SUS at 100F. Same thing with but different numbers at 212F. If your spec calls for 10W and you use 15W, the 15W oil, at 185, could be very close to the 170 upper limit for 10W. However that 15W oil could just as easily be at 350, which is a long way from the 170 limit for 10W oil. These numbers are approximations from the chart, but illustrate the point.

If there is a lubrication engineer out there, maybe they can shed more light on the subject.

Andy

 

[gordon]

That must have been one good class thats for sure. Some eye opening info I never would have thought such a wide range could be considered the same wt.
Thanks for the info.
Gordon

 

[JBM]

Sorry not to be able to address you by username. Your viscosity info is "eye-opening" and sure to cause me some rethinking about which oil to use. One question. Does the variation in SUS numbers hold true for both petroleum and synthetic oils?
JB

 

[Bird]

Andy, I find it interesting that my B2710 manual goes into such things as "Distillation Temperature, Viscosity Kinematic, Viscosity Saybolt (SUS), Sulphur Weight, Copper Strip Corrosion, and Cetane Number" for the diesel fuel, but not for the lubricants. Sounds like an interesting class you attended.

Bird

 

[Anonymous Poster]

JB, yes the variation would hold true no matter what kind of oil. If a manufacturer makes oil of any kind and the SUS number falls within the SAE range at any point, they can call it the weight oil for that range.

In the class they talked briefly about synthetic oil. It was pointed out that synthetic has some superior properties, in fact many industrial gearbox manufacturers will allow the horsepower rating to be increased 20% if synthetic is used. However they also said that because of the increased cost, synthetic oil was not recommended unless that horsepower increase was required or if longer intervals between oil changes were needed because the gearbox was very difficult to get at to change the oil.

The instructor strongly insisted that any lubricants that contain extreme pressure (EP) additives should not be used in any gearbox that contains a wet brake. The reason for this is the way the wet brake works. As the brake is applied, the oil film is wiped off the surface, and the breaking action begins. The extreme pressure additives in oil will prevent this braking action from occurring properly and will often result in a sudden and very expensive failure (tearing out) of the braking surfaces, just when the brake is most needed. He pointed out that all synthetic oils have these extreme pressure properties no matter if they have the additives or not. He stressed that synthetic oils should not be used in a gearbox with wet brakes. If there was no other choice then the internal brake should be removed and an external brake added. As he was telling us this, I could not help but think of the Kubota transmissions with wet brakes.

Andy

 

[JBM]

Just when I thought I had it figured out!! Thanks for the info Andy. I called Amsoil again and talked at length to a different tech person. He, like the first Amsoil tech guy, said it is fine to use the diesel 15W-40 in my Jeep's gas engine that specifies 10W-30 (which by the way comes from the factory with "synthetic" gear oil in the rear differential). Your point about high pressure lubricants in gearboxes with wet brakes makes sense, and sounds like it may apply equally to my motorcycle which has a "wet clutch". I'm still going to try the Amsoil engine oil but guess I will play it safe and order a case of both the 10W-30 and the diesel 15W-40. Thanks again.
JB

 

[MChalkley]

I talked to an Amsoil engineer and he said there had never been any such failures in any equipment using their synthetic lubricant reported to them, nor is there any reason there should be. For that reason, they warranty their product against any type of failure, including this one, if such failure can be attributed to the lubricant. He further said that EP additives are a known source of this problem, though it is rare. He also said he had heard of such disinformation regarding synthetics being bandied about before - apparently some people assume that, since synthetics have similar EP properties as non-synthetics using the additives, they must behave similarly. Nothing could be farther from the truth - they arrive at their performance characteristics from differing approaches.

However, as will always be the case, if someone doesn't like something, reasons can always be found, or invented, to bolster one's position.

Mark

 

[PaulB]

Mark already knows this, but just reading about you guys calling amsoil and talking to this tech rep or that tech rep reenforces what I had said in a previous post - like their product or dislike it, you can not argue the fact that amsoil is a very consumer oriented company, which makes communication easy and rewarding. Any of you guys have any trouble getting through to the people you wanted to talk to? I doubt it. Like I said before, just try to talk to the chief engineer in the R and D department at Mobil or Texaco (or kubota for that matter) and see how far you get.

 

[Anonymous Poster]

I am not an oil specialist and do not know for sure if what I learned in class is true. It certainly sounds reasonable. The class was given by an organization with no ties to any company or industry and because of this, no hidden agenda. I am only trying to pass on some knowledge that may help others. I have nothing against synthetic oils, the company I work for uses them in the gas turbine engines we make, and I have used them on more than one occasion at home.

Almost all of the things I have read in these discussions in favor of synthetic oil have been to reiterate the opinion of an engineer/salesman from an oil company. This is not an objective source. The motive of the person at the oil company is always in question. That is not to say all their advice is false, but it may be shaded in favor of their product.

For example: every time you have a question about cars or trucks you always call the Ford motor company to get an answer, and all the people in your discussion group also always call Ford with their questions, and you discuss the answers, and there is very little information from any other source, pretty soon Ford cars and trucks start sounding a lot better than all the other brands. This may or may not be true.

If someone does like something, reasons can always be found, or invented, to bolster one's position, I am trying to be objective and pass on some information, please do not take offence.

Andy