So the 15w 50 is good for the motor, and the v-twin 20w 50 is good for the tranny?

 

IMO, I think the 15w-50 with its friction modifier is better for the motor than the V-Twin oil without. For the tranny, I prefer the Mobil-1 75w-90 Gear Oil, but the 20w-50 V-Twin oil is OK.

My bike's motor has been run solely on the Mobil-1 (automotive) 15w-50 synthetic. Below is a Blackstone Oil Analysis done on the motor oil at 78,675 miles. I'd say that the results speak for themselves. If you don't understand all of the numbers, just read the comments section.



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V-Twin formula, overpriced and unnecessary

Use 15W50 in the engine, although you should use something else in the tyranny and Primary

 

I changed to that same gear oil in the trans (after using Harley trans fluid non-synthetic for the 1st 22,000 miles) and within 500 miles of the gear oil, my stator went bad. It did have 22,000 miles on it so it might have been time for a bad stator. This time I used the Screamin Eagle Motorcycle lubricant fluid. 3000 later and the stator is still working.

I have the v-twin 20w 50 in the oil now, but I need an oil change so I think I will go to napa and get the 15w 50 this time

 

The stators Harley uses are pretty crappy. I've gone through 3 as well before replacing it with one from Cycle Electric that's built much better, and no more expensive.

The Mobil-1 75w-90 Gear Oil did not cause your stator failure, and it's perfectly safe to use in the Sporty primary/tranny. The Mobil-1 Gear Oil is not corrosive and will not harm the stator. I just did a thread yesterday on Gear Oil and which ones are corrosion safe. You can find the thread HERE.

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You are the best cHarley. I will do the oil change with the 15w 50 this time for sure. and keep with the screamin eagle in the trans

Thanks

 

Thanks man. I may change to the 15-50 next time. 75-90 in the trans as usual

 

I was at the HD dealer today to get what I need for the chain case / trans oil change.

I asked the parts guy for Formula+ trans and chaincase lub.. and then asked him if there was something better.

He told me to put Mobile 1 20w/50 Synth in the chaincase and in in the engine. I went with the Mobile 1 20/50 for the chaincase which is the same I have in the motor.

Here is another opinion from HD

http://www.mobiloil.com/USA-English/...Davidsons.aspx

As an aside, he told me if you put the wrong oil in the chaincase you'll mess up the clutch.... What's that about?

More here - http://www.nightrider.com/biketech/hdclutch.htm

Q: What about using Synthetic Oils in my clutch?
A: Synthetic oils, by their very nature of better heat resistance and improved lubricating properties, would seem to have an advantage. This is an advantage when it comes to lubricating an engine or transmission, but turns into a disadvantage when used in a clutch. This increase in lubricating properties (they are slippery) can cause an old, worn out clutch to fail. The purpose of the oil in a wet clutch is to cool, not to lubricate. The more 'slippery' an oil is, the more likely a clutch is to slip, resulting in increased heat and creating excessive wear.
While most high performance clutches are designed to work with synthetic oils, it is not recommended that they be used by most clutch manufacturers. Synthetic blends are usually considered acceptable.

 

The V- Twin is 20-50 Synthetic