OK, I know this has been talked about before; but if it were your bike would you use Amsoil in your rubicon? Amsoil states that it will work fine, but I didn't expect them to say any different. My knowledge of the importance of the oil consistency in a hydrostatic type transmission is lacking. I know the Hondamatic is a slightly different design, but does anyone have any experience using synthetic in hydrostatic type applications?

 

I also will be switching oils in my Rubicon the next time I do maintenance. I wasn't around for the earlier discussions so I wouldn't mind rehashing some of the topics.

I have noticed that the oil used in the Rubicon is very, very thin. It flows like water. The only other oil I have ever seen flow like that was a Mobil 1 synthetic. It was a 0W-30 for winter automobile use.

From the Rubicon repair manual, "Honda GN4 4-stroke oil or equivalent motor oil. API service classification SF or SG Viscosity: SAE 10W-40."

This should mean that any 10W-40 motor oil that meets the API SF or SG service classification, should suffice. These specs are usually given on the side of the oil container. Does this mean that a synthetic 10W-40 will work? The big discussion always becomes: Does synthetic adversely affect internal seals?

I don't know. I know from my work in the hydraulic industry that some hydraulic fluids will attack some rubber compounds. Typically, these are fluids that are used in aircraft applications where a non-combustible fluid is specified. This problem was solved with the introduction of Viton rubber compounds.

I have used synthetics in all of my cars including a modified Mustang that I beat the heck out of. I have not seen any adverse side effects. In fact, it seems to run smoother and quieter.

My question is, what happens when synthetic oil breaks down? All oil breaks down. It gets diluted by unspent fuel and undergoes chemical changes as it gets heated and cooled and mixes with the carbon that is a by-product of burning dead dinosaurs.

I doubt I was any help, but maybe I can learn something too.

Good topic, I hope it isn't too old to give some more consideration.

 

Amsoils new motercycle oil would be awesome to use.. run 10W40 and your set. Some say snythtics are to thin and cannot protect the valve train during starup but my 1983 XR500R has zero wear even after 50,000 miles of hard dune abuse. All my friends who use havoline 30W have had at least 2 top ends in the same time frame