Pete, my understanding of the leak tendency in synthetics is the fact that most of them contain excellent detergent additives. In older engines that have been running fossil oil and have developed some level of sludge and varish, as this gunk is gradually cleaned out with the new oil it uncovers gasket and seal problems the sludge and varish has been masking.

That said, I ran a '96 RK 106k miles on RP 20w50 in the engine and 75w90 gear oil in the tranny, with never a problem with leakage, even with the base gaskets. In fact, the rocker covers and heads of that bike were never removed. However, late in my ownership of this bike I changed primary fluids from the HD fossil variant to HD Syn3, and I soon began having a minor leak (more like a seapage) problem in one place at the inner-primary and engine case near the front jug. It would only seap when the engine was between cold and hot, and after about six months of this I changed back to the fossil oil. At that point the seapage stopped, which makes me wonder. There was no sludge in the primary, so what caused this minor leak? Smaller molecules with the synthetic oil?

 

I read that crap a while ago. HD oil is cheep CITGO oil, not even full synth. Even if it was good, do you really want to support Castro's protochae, Hugo Chaves? CITGO is wholly owned by the gov. of Venasuela. Harley and their dealer network has a long history of disinformation. Slick 50 had additives that were traced to engine failure, I think it was some type of teflon.

 

Hey Pete (ZD),

First off, thanks for the reply. Secondly, "called out"... figure of speach, I'm glad you posted.

You've piqued my curiosity about the specific application of the turbomachinery you work with. With oil capacities of up to 1400 gallons....I ain't gonna lie,,,I'd like to have a piece of that[sm=drooldude.gif].

More importantly though is that my experience with full synthetics is exactly the opposite of yours.
The cycloidal reduction gear boxes I mentioned had experienced leaks for several years using the manufacturers recommended lubricant, a mineral based grease and one with a highly recognized name. As the grease began to breakdown with use, it seperates into its lighter fractions and heavier fractions. The lighter fractions of the lubricant were finding thier way past seals. Often migrating across input shafts into motor housings...and POOF!, $10,000 motors are toast. Sometimes the oil would migrate completely through the motor to a safety brake... Oil + brake = Well, you know.

This can happen when petroleum based lubricants are used past thier useful life. This is due to the widely varied size, shape and weight of petroleum moleculesand thierresistance to mechanical, heat and other stresses placed on the lubricant. Even with high end additive packages to counter this weakness, depending on the application, these additives can degrade fairly quickly.

Although a hydromechanical engineer may have some knowledge of tribology, his expertise is in the study of the mechanics of fluids or the laws of equilibrium and motion concerning fluids. Not the science of the mechanisms of friction, lubricantion, and wear of interacting surfaces that are in relative motion that is a tribologists field.

If comparing molecular structures of petroleum vs synthetics, particularly polyalfaolefin (PAO) synthetics.
Petroleum molecules, as stated before, vary widely in size, shape, weight, and resistance to many different elements. This fact gives petroleum oil the propensity for the smaller, lighter molecules to find a breach in a seal, as in the cycloidal gearboxes referred to earlier. On the other hand, PAO synthetics which are in fact hydro carbon molecules, are large molecule hydrocarbons, some 6-10 times larger than the average petroleum molecule. The fact that the POA molecules are extremely uniform in size, shape and weight lend to thier ability to form a better, more efficient seal, lessening the propensity to leak. Also exhibited in the cyclo's.

Now if we are talking about Polyol Ester (PE) based stocks, that may be a different animal completely. The PE synthetics are particular about thier compatability with seal material. The properties of PE could possibly be described as "wicking", although I've never heard that term used in this regard. Seal swell has been a long standing issue with the use of PE based lubricants. The trade off here is that Polyol Ester's extreme ability to remain stable at very high temps is desireable in some applications (maybe yours). A less favorable trade off would be PE's marginal hydrolitic stability...don't mix well with water. Polyol Ester tends to emulsify in the presence of water and has poor demulsification abilities. This action is known as hydrolysis, the chemical decomposition in which a compound is split into other compounds by reacting with water.

Regarding your use of the word "organic". Typically organic describes chemical compounds existing in or derived from plants and/or animals. However, upon further research, it seems the definition has been expanded to include all other compounds of carbon. I stand corrected

In the end, my issue with your post was your broad statement that "Synthetics" leak more due to molecular st

 

For all the BS on synthetics and roller and needle bearings has anyone considered what's in a two stroke engine. Seems to work ok for them. Onlythree thingswill cause a roller to skate. Eccessive heat causing lube breakdown, and bearing overload. Sometimes it could be cause from debrilocking the roller as well. That sticky oil crap makes me laugh. Amazing how an oil could be trained to stick only in one spot to make the roller turn. What about the cage and the outer race? Thick oil is not your friend either which makes the case for good warmups before blasting off at high loads.
Ron

 

Well I have read this whole thread, and I have to say my biggest concern is ZD's revalation that I can't pot Amsoil in my sandwich.

I had absolutly no problems when I used dino oils as my spread of choice, although my tomatoes did on occasion developesemi circularshaped galling.

By the way Redline shockproof heavy makes a superb ice cream topping when you run out of strawberry syrup. Which of course proves Redline's way better than Amsoil.

[sm=icon_quiet.gif]

 

Steve: I personally will use your product once my new bike has been broken in. That's if they canever find the damn thing for me. There are several issues that have come up in aircaft engines that will show that pure synthetics are not the be all end all of oils. This is based on my aircraft experiences. Turbine engines only have success with synthetic. End of story. Now the piston engines are a different animal. Back in the late 70s or early 80s Mobil got their foot in the door with synthetic oils for reciprocating engines. All was well for a while until these engines got to around 400-600 hours of operation. They all suffered from extreme sludge buildup. That was the end of Mobil. At the time, it was discovered synthetics had no cleaning properties. They all went back to conventional aviation oils. Only recently has there been some oils that contain synthetics. Aeroshell 15/50 is the most common with about 25% synthetic and the rest dino. That way the benifits of synthetic could be used, and the cleansing of conventional oils could be kept. It would appear from field experience that this particular oil even though only 25% syn has a nasty habbit on some engines to leak far more than conventional. It would also blow it out the crankcase vent at a greater rate. I attribute most of this as a seal/engine condition indicator more so than a flaw in the oil formula. It would appear that synthetics will flow better into tight fits, which is why they may offer better lube qualities for those areas but at the same time if there is a weak gasket or marginal seal in the area it will tend to find it's way through it also.
To me, if it leaks, the problem is with sealing technology, not the oil.
Does Amsoil contain some detergents or dispersents unlike the early Mobil failure in aviation? For what it's worth, no aviation oils have detergents. The newer multis and hd versions only have dispersants.
Ron

 

I've been cussin' and discussin' this issue, and I've soaked all in that I can. I thank you guys for all the info. I've got 5,000 on my EVO re-build (SE heads, EV27 cam). I've got 2 more oil changes left in my oil stash, and then I'm going to change to synthetic.

I thank you guys for all of the information...

 

How many 1 percenters use synthetic oil???

"Hey if this doesn't lock this thread down nothing will"

Saint

 

Have been useing Amsoil 20/50 for better than 30k miles and have loved it from day 1. The engine is quieter and the tranny shifts better. Don't know about the evo harleys but it works great with the twin cams.

 

In my opinion (as I have read in some articles) synthetics are far superior especially in extreme temperatures. In hot weather, they slow down oxidation which destroys an oil's lubricating properties. In a cold environment, synthetics flow sooner, which protect our preciousbig twins a lot better than dino oil. Synthetics lubricate faster especially when starting your bike at the start of your firstride for the day. As operating temperatures rise, heat becomes the main enemy. For dino oil, 250 degrees farenheit is the figure to remember. For synthetics allow for under 300 degrees before you get worried about oxidation. As long as sustained operating temperatures don't go beyond 250 degrees farenheit, you can sit back and relax, as your engine is "cool" with dino oil.

Igo forMobile1 fully synthetic5W 50 fluid and the engine runsexcellently evenat higher temperatures here in the Philippines, a hot tropical country, situated on the equator.