I know this has been covered here before but who uses one oil for the engine, primary, and transmission? What brands and weights are being used and why use the same for all three, convenience? Thanks.

 

Synth3, which you can get at the Harley dealership, or use the appropriate 20w50 synthetic oil, safe for your clutch. (Non-Energy saving) You don't HAVE to use Harely's oil.

That's the whole story behind the name, Synth3. Same Synthetic, in 3 places.

I prefer 20w50 in the motor and primary, but 80w90 Synthetic (Redline) in the trans. Shifts smoother, to me at least...

 

Hall1836… I’ve got an 07’ Dyna Low… at 1K, dealer switched out all oils, tranny, primary, and engine to Syn3. At about 2.5K, a local Harley mechanic was spreading the word to replace tranny fluids with Redline Heavy ShockProof Gear Oil. His take was it would greatly increase smoothness of shifting, quiet tranny down , and produce near zero wear… So drained out Syn3 from tranny and surprised (and angry) to find the plug magnet junked up with a silvery gook indicating some serious wear going on… replaced fluid with the Redline as recommended and noticed an immediate difference in the tranny operation and noise (lack of), even kicking to neutral seems easier… thought I’d see what the primary plug looked like so I pulled it too and found some, though not as much, silvery gook on it too… it was then I decided to shift the primary and engine fluids over to Mobil One V-Twin Syn. At 5K, replaced all the fluids again just to see what the plug magnets looked like and they were all clean, free of any debris… Sooo… all that being said my new scheduled maintenance for fluids will be every 5K change engine oil with Mobil One V-Twin and oil filter, every 10K replace primary fluid again with the Mobil One V-Twin, and every 10K replace the tranny fluid with the Redline Heavy ShockProof Gear Oil… That’s my 2-cents… R/ Ed H. VaBch,Va

 

Yup - amsoil 20/50 in all three holes.

 

I use Syn 3 in the engine , Harley primaryin the clutch and Mobile 1 75-140 in the tranny ,it shifts real smooth with no loud clanks between shifts

 

I did so much research on this my head was spinning....lol. I just went in for my 1000 mile service and decided to go with Amsoil 20-50 in all three. Dealer said that and Mobile one was what most people run. WOW was my tranny much more smooth when I left....Big difference and I'm very happy with the Amsoil.

Just like anything else....everyone has their own preference.

Be safe

 

I put Royale Purple 20/50 synin all three holes .Had Harley syn before, notice one hell of a difference in the shifting a lot smoother with the Royal Purple.

 

I use M1 20w50 in the crankcase, M1 75-140 in the tranny and HD primary fluid in the primary. Amsoil and Redline are good products, too.

I recommend staying way far away from Syn3 crap. Lots of much better products out there.

DougJ