If you must use Mobil 1 or any other oil just use 10w40 in primary and 20w50 in tranny. Or just 20w50.

I'm using Syn3.

 

You might consider that while legally labeled full synthetic, Syn3 is technically not full synthetic oil according to the MSDS. It would be foolish to believe this is done to save money. They could use full synthetic if they wanted too and sell it for enough to cover the cost. There are important reasons why they blend in base oils that are not synthetic. Seals, bearings, gears or whatever the case may be. Harley is designed for high mileage.

Ford diesel oil is a very similar product. I only use Motorcraft diesel oil in my truck and it is a synthetic blend. Not because it's cheap oil but because it is best for the engine.

 

Castrol 4T 20w50 in all 3 holes in my Breakout.

 

I got to agree with this with that said reading these posts are helpful, still planning on what my long term oils will be. I do like to use conventional oils in a bike, just my own thing, since I change often. But it's great to read different points of view.

From what I have been reading, using a GL5 gear lube may not be a great idea in the transmission and that MIGHT also include GL4. The GL5 extreme pressure additives can and do attack gold metals on the transmission such as brass and copper alloys and to various degrees cause corrosion. Depending on the make of gear lube, some worse then others.

Using motor oil or Primary+ do not contain these corrosive extreme pressure additives.
From what I understand Primary+ is a straight weight 50 oil but need to confirm that. I can see some benefit from a straight weight oil as it won't shear down over time in the transmission so have been thinking IF Primary + is a straight weight 50 it might make sense to use a straight weight oil like VR1 50 or just stay with the Formula+, I just wish I could see more UOAs on the Formula+ as VR1 already has many UOAs and stellar results with their multi viscosity race oils in Harley engines.

Anyway back to oils, even Amsoils site recommends their 20/50 in the transmission over their gear lube and if Harley thought a GL5 gear lube was the way to go I am sure they would have.

 

If GL5 meets MT1 and MIL PREF 2105 it will be yellow metal safe. Just gotta make sure friction modifiers are not part of the formula and it will be good.

Formula+ is a solid 20W50 oil spec or 80W90 gear lube spec. Flash point is very high. pour point is -51, thats very good for how viscous it is. Speced out at GL1 but meets GL3 requirements as well.

A GL4 would not be a good idea. I have not looked hard but every one I seen uses unbuffered sulfur. They do not meet MT1 or MIL PREF 2105, so dont use GL4. It will eat up yellow metals.



Harley Davidson Formula+
Application: recommended for heavy-duty service in manual transmissions where the manufacturer normally recommends either engine oils or GL-1 lubricants.
Specific Gravity: 0.857
Pounds per Gallon: 7.14
Viscosity, ASTM D 445,
cSt at 40°C: 168.04
cSt at 100°C: 20.10
Viscosity Index, ASTM D 2270: 139
Brookfield Viscosity, ASTM D 2983,
cP at -26°C - 28,800
cP at -40°C - n/m
Pour Point, ASTM D 97, °F (°C): -60 (-51)
Flash Point, ASTM D 92, °F (°C): 507 (264)

Im sorry if you dont know how to read that, but thats what it is. 10w40 in the primary will be too thin. TSC has a 2 gallon jug of GL1 but it specs out thinner than Formula+. The primary and trans likes the slightly thicker F+.

VR1 is a great strong oil. i use the synthetic version and it is the easiest low temp starting 20w50 I have put in the Harley engine. VI is high and its more viscous at operating temp than most synthetic JASO MA2 synthetics.

 

Great info, I like seeing the "numbers" and also run UOAs on the different oils I tried over the years. Personally I wouldnt use a /40 oil in any bike, including my past liquid cooled ones, except as a winter oil, its gets hot here in the middle of SC.

I understand the MT spec as well but I think there are many running gear oils without taking that into account.
I have read the Primary + is a solid oil, just no UOAs or VOAs on it.

Im a fan of Valvoline oils I have yet to see a "bad" UOA on a bike using any number if their products. Personally I became a fan of their 20/50 4 stroke motorcycle oil in my vstar 1300, had great UOA on it, could buy it in Walmart for $4.00 a quart, though not the reason I used it, I used it because in Amsoils own 2009 study of motorcycle oil, Amsoil used the conventional Valvoline 4 stroke oil pitted against a whole slew of synthetics and the darn Valvoline beat or met many of the syns where I think it counts, 4ball wear test and gear test.
I then noticed their VR1 does very well in Harleys too and yet, I see the Harley 360 seems to be a pretty respectable oil, I assume the Primary + is as well.
My feeling is to stay with the Primary plus in the Transmission/ Primary and after a couple UOAs on the 360 from the engine, try the VR1 and/or 4 stroke again, just to compare.
I do wish, I could see a UOA or VOA on that primary plus and a spec sheet showing what is in it, just for the hell of it.
Thanks for the feedback.

 

Everything I see on VR1 is so strong that I wont do a UOA on it unless something funky happens. Same with Formula+. every time I change it there is so little fuzz on the magnet it just wipes off in one swipe with my finger. Thats running it in the sportster too where the same fluid is being eaten up by the clutch and the trans.

On a side note about Valvoline, I had a loooong power outage last month and needed to get the break in oil out of a new generator being broke in on 70-90% load. Picked up syn power and ran it for the next 50 hours straight like the manual said to. Checked oil every 10-12 hours, did not burn a drop. Was out of power for 10 hours couple days ago. Decided to leave the oil after the big outage in there with 50 hours on it. 60 hours on it now and its still at the top of the threads. It will easily go 100 hours on a change running hard at 90% load. For some reason their oil does awesome in air cooled engines.

Still run Castrol high mileage in the car and truck because its the strongest blend oil I have used. But my air cooleds get Valvoline synthetic, 10w30 for OPE and VR1 in the ride.

 

When I see the VR1 UOAs I wonder why anyone would consider anything else, yet, I dont run it, not yet anyway. Its does very well in Harleys.
Im a month or so away from the next oil engine oil change, will make up my mind by then. For the winter it maybe a 10/40-20/50 conventional mix or 15/40 diesel oil or a 20/50 syn.

I guess Ill stick with Primary + in the trans and primary... then again, have all winter to think about that. I guess I will always wonder if anything better out there.

 

I'm going to try Amsoil 75-110 Severe gear oil and see how it works. I have tried and liked the Redline Shockproof Heavy but I have read a lot about the Amsoil too.

 

I've used royal purple 75-90 and 75-140 and shockproof and various 20-50's. I think the gear oils make a smoother quieter 6 speed gear box but that's just my observations no science involved.