A great many of you are using gear oil in your transmissions. I would like to present somthing to think about. Most all metric bikes share the same oil with the engine and transmission. That means that the oil must be able to withstand both type of environments such as shear, high temps and contamaination from normal combustion of the engine. Looking in stores at gear oil and reading the lables I haven't seen where the gear oil says it is recommended for motorcycles. Now I have not looked at all brands and maybe I am wrong but I have looked at Mobile 1 gear oils of all types and none say they are for motorcycles. Amsoil gear oil also do not say they are for motorcycles as a matter of fact they recommend MCV 20-50 motorcycle with the following and I quote"Amsoil performs like a gear oil without the negitive effects of extream pressure additives". I will contact them soon and ask what they mean by that. Anyway something to think about.

 

Are you saying we should not use gear oil in our bikes just because there is no mention of motorcycle on the label?
Think about it.The tranny on a HD is no different than a manual transmission in a car or truck.It is seperate(most models?)from the motor,has gears,bearings and shift forks.

 

HdJoe: No problem with using either here, but trannys will chew up most multi oils polymers and need more frequent changes in order to maintain protection as they get thinner and thinner with use. Gear oils don't care about that as they have none or very little of that and really never lose lube qualities or viscosity. Contamination is usually the reason to change them. EP additives won't hurt the new HD tranny but it won't work either. You need to be pulling a plough in order to generate enough friction on the teeth to make these additives work. Basically a waste of extra money. Standard gear oil is plenty. I need to point out as has been mentioned before tranny oils are not that heavy in viscosity. Most work out to about the same as an engine oil of around 40-50 SAE.
Ron

 

I'm not saying anything. I am a liitle courious why Amsoil talks about Negitive effects of additives in gear oil. Also look at all those other big bore bike that are air cooled the share a common oil pan. they don't have ny tranny problems. I just presented a thought nothing more.

 

One or the other will suffer without the proper lub viscosity unless it has been engineered to do so.Use what Harley reccommends and you will not have any problems.Amsoil products are certainly top of the line.