What is the best oil for a Harley transmission and primary?

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As much I love HD....I hate to say it, but HD doesn't know SH*T about synthetic oil. For decades, they said not to run synthetic in their engines.....because of popular demand by the public, HD finally came out with their SYN3 synthetic oil several years ago, but it is honestly not worth a crap. THE BEST 3 SYNTHETICS FOR A HARLEY ARE

#1-AMSOIL, #2-LUCAS, #3-MOBIL1(which is recommended by S&S). I have been working on HD's and building performance engines, drag racing and dyno tuning for 20 years and have been running Amsoil for years, but have recently switched over to Lucas because it is just as good, but a little cheaper. AND THEY DO NOT AND WILL NOT VOID YOUR WARRANTY

FIRST OFF.........DO NOT RUN HD SYN3.....IT'S JUNK.........I AM A CERTIFIED HD TECH, AND I WILL TELL YOU FIRST HAND....HD DOESN'T KNOW JACK ABOUT OILS!!!!!!!!!

For deacdes, HD said to never run synthetic in their engines, their reason....it will cause the bearings to "skate".........but ask anyone on the drag strip running a top fuel 800+ HP engine what they run.......FULL SYNTHETIC.......their bearings don't skate!!!

By popular demand of the public, HD finally released their SYN3 back in the early 2000's......manufactured by Sunoco. SO........

Second......why would you WANT to go longer between oil changes?......esprcially on an Ultra, the baggers are subjected to to more engine strain than the other models due to their weight, plus they run hotter from not as much aie flow, that's why they have a larger oil tank to aid in cooling. FRESH OIL IS CHEAP INSURANCE AGAINST ENGINE FAILURE. Standard oil you should change every 2500 miles. You CAN go about 3500 on synthetic, but why? Scheduled PREVENTATIVE MAINTENANCE set by the factory are based every 2500 miles, IT IS BEST TO CHANGE YOUR OIL EVERY 2500 MILES....SYN or STD. Keeping up on the maintenace, prevents major breakdowns. It's btter to spend $400 or so a couple times a year than spend a few thousand to repair something that was caused by lack of maintenance.

As the other guys have said, synthetic does make your engine run cooler and lubricates much better than standard oil.

The best synthetic to run is 1) AMSOIL or LUCAS 2) Mobil 1

It is ok to run the same synthetic in the primary as you do the engine.......but NEVER use that same oil in the trans. HD says you can, but it makes the trans hard to shift and noisy......run minimum 75/90 gear oil......best if its 85/140......the absolute hands down best trans oil on the market is RED LINE full synthetic Shockproof 85/140...it will make your trans runs smoother, quiter and shift easier.

Harley Transmission Oil

Harley Primary Oil

Biker Bob is correct except it should be 3.5 quarts in the oil tank with a new filter.And don't use that overpriced Harley junk oil.Give it some good stuff.I run Mobil 1 V Twin(Amsoil and Lucas are great oils too) in the engine and Redline MTL in the primary and Redline Heavy Shockproof in the transmission.

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RE:

What is the best oil for a Harley transmission and primary?

I've kinda narrowed my choices down to trying either Redline or Amsoil in my 2002 Electraglide.I just thought i'd see if anyone has experience with either of these and what they thought.Also does anyone know of something better particularly for the transmission?Thanks in advance.

Hey Andy,... I was using the Lucas in all 3 holes but at 7,500 went to the Lucas full synthetic 75/90 in the tranny. I kept the Lucas 20w50 full syn for the motor/primary.

I have over 35K on it now and I love it.

I have a buddy in Plano Tx that swears by the Red Line shockproof 85/140 (he drag races a sportsman class bike and R/L gives him as much as he needs) I have seen some of the tranny teardowns and his gears look amazing every time...

There is alot of popularity for the Amsoil product line. I personally have not used it, as there is simply not a dealer around close by but a couple of guys I talked to out of Corpus Christi say its top shelf all the way.

I use Amsoil 20W-50 in the engine, Amsoil 10W-40 in the primary, and Red Line V-Twin in the tranny. I think the lighter oil in the primary reduces viscous drag in the clutch and allows cleaner release and reduced "clunk" when shifting gears.

Do not run Amsoil in your engine or primary I ran it for years and found it to be junk trust me I am a tech as well, and had to replace a lot of worn parts due to poor oil lubrication.

Awesome post, ordered 20-50w amsoil for my primary and engine. Then I ordered heavy weight shockproof oil by redline for the trans . Found it all on ebay.

i have 07 Heritage and run amsoil synthetic in all 3 places, my last oil change i went 75/90 in trans but amsoil synthetic in crank and primary, dang primary gets hot , i also have 04 FXST STANDARD SOFTAIL i never had any problems at all . not when i put it in gear 1st it does clang , i was going check on liter oil maybe auto trans fluid? the 4x4 truck trans fer case uses automatic trans fluid ?

what has any one figured out heritage has 25k on it standard has 14k

if trans is whining in 5th gear use 20/50 w half a bottle of there oil additive put additive in 1st so yo I had same problem and that was 20k ago and still hasn t made any whining of course that was doing the same thing each service