And even though changing every 15 hundred is goid , it will still run hotter.
Not good IMO in daily stop and go

 

2006 Streetglide. I used the HD Syn3 in all 3 holes until my cam bearings went out at about 32K. The cam compartment was totally rebuilt using Timken bearings. I then switched to conventional HD 20-50 in the engine and Formula+ in the transmission and primary. The bike now has 91,000 miles on it and have had no oil related problems with engine, primary, or transmission.

On a recent 3500 mile trip I added 8 oz. oil and this about the same amount of oil it used 40K miles ago. I assume there are a lot of good oils out there but I don't see the advantage of trying/using a bunch of different oils when the HD oil works this well.

Shortbox

 

Charlie, try Spectro 25w60 in your bike.

I have been using it in my '01 Superglide and my '12 Streetglide.

it is a petroleum oil, but I change every 3-5K.

Everything runs quieter.

I DO NOT run it in my trans or primary, just the engine.

Ken

 

Run whatever gives you piece of mind. we overthink the situation. I run Shell Rotella in everything. My big equipment 15000 miles or yearly. Have 900,000 on one cat engine

 

I live in a city. I put about the same amount of miles on my vehicles per year. Including my bikes.Never dare to go that long between lubes. My vehicles never last that long. And they're mostly runnin on sinthoils.
Maybe I should move to the country. Is it the air?

 

I have a long history with gear manufacture and design. To make it short and sweet run Gear oil in your Harley transmission. Doesn't matter if it's synthetic or conventional as long as it's gear lube. That's why they make gear lube in the first place. Reason is because gears slide on the gear tooth under rather high pressure. Harley transmission gears are either 10 or 12 diametric pitch, which results in roughly only about 1.2 gear engagement. Or a little over one tooth at a time. Dealers are seeing a lot more transmission repairs these days due to using engine oil. That was never the case before as in the old days we ran gear lube and a Harley transmission could pull a 4 bottom plow, it was and is built that tough.

 

One week ago 5200 miles on a 17 RGU i changed out my SYN3 to tranny oil to Spectro
Platinmum 75w 140. I have read and heard tranny oil makes a difference. After one week with the spectro i have notice a nice differents with my Bike it goes in and out of neutral a lot easier then ever. Also no more clucking from neutral into 1st and a whole better shifting for me. Love the way it's preforming.

 

PDB, the original post here is 11 yrs old, that's a record for me. I run Syn 20W50 in motor, syn 75w140 in the trans and dino (Rotella) 15w40 in the primary. I have for years, no failures.

 

Checkers thanks for the reply I run Rotella in all my other bikes love the stuff myself. Just a little hesitant to run it in my 17 RGU M8 motor yet. But a good tranny oil is worth the money

 

@ checker; have you ever run synth lube in primary? If not? Than why?
Do you consider the primary a least troublesome section of the system?