In the primary, the cheapest type F ATF will work fine. You're crazy to use expensive stuff in there; it just isn't necessary. All you're doing is lubing the chain and cooling the clutch. In the tranny, throw some syn gear oil in there, and no more miles than most of you ride, you can just forget about it. For the engine, any name brand 20w50 will do, syn or not.

 

Thanks for everyones input!

I went with the mobil v twin synthetic and the mobil synthetic gear oil.

Shawn

 

Funny you would ask. I just had a conversation with the service dept where I purchased my new 2009 Fat Bob. I just bought the bike 3 weeks ago and am getting close to it having 1000 miles on it and I wanted to be prepared and to furnish my own oil. I told them I wanted to use Amsoil fully synthetic and they said no problem. They said if I were going to use a synthetic 20W-50 motorcycle oil that they would use the same thing in all 3 holes. So I have ordered two gallons of the Amsoil MCV 20W-50 and an Amsoil chrome filter for it. The way it's going I'll need to have it serviced in about 3 weeks and so I'll be switching to Amsoil. I really believe that it is very good oil and I use Amsoil in all my vehicles, including the lawnmowers.

 

I'm running Rev-Tech 25w-60 in the crank and primary and Bel Ray in the trans. I noticed a big difference in shifting with the Bel Ray, good stuff. One thing to remember, no matter what anyone tells you, synthetic oils are not any "slipperier" than conventional. I've had this argument with many people. An SAE viscosity rating is standardized. If a 20w50 synthetic was more "slippery" than a 20w50 dino oil then it wouldn't be a 20w50! The only difference is the resistance to thermal breakdown in extreme situations. There are a lot of good oil products out there, you just have to educate yourself to sort through all the bull****.

 

I use Mobile 1 in the engine, Redline HD shockproof in the tranny and primary case.

 

Here's my experience. I used mobil 1 15-50 in my 2005 dyna since the first oil change. When i pulled the top end and cams out at 36,000 to go 95" everything inside looked like a brand new engine. I didn't even see any visible wear on the cylinder bores or pistons. Only thing showing wear was cam chain tensioners. In short i was amazed as i had ridden this thing hard and fast. Soon as i got my 07 Road Glide the harley oil came out and mobil 1 went in. Now i did run SYN 3 in the primary all that time and it caused my engine sprocket to wear out!

 

I saw where some guy put 20/50 synthetic in his tranny. I wouldn't do that. Here's what we learned early on when HD suggested SYN 3 for all 3 holes and some of the guys ran it in trannys. It seemed ok because you only had to have one kind of oil. There were a lot of failures because we rode hard at high speed. It won't take heavy loads. i assumed it would be ok in primary and good for the chain but at 36,000 my engine sprocket teeth were pointy and i had a hydraulic tensioner so it was in adjustment. I run the HD new type primary/trans oil in primary now and it does great.

 

While I agree that a conventional oil is not less "slippery" than a synthetic, what I've highlighted above is incorrect. Viscosity is a measure of a liquid's resistance to flow, or in more conventional terms, its "thickness." It has nothing to do with how "slippery" it is.

The whole notion of synthetic being more slippery started because synthetics do have less internal friction than conventional oils. This is the primary reason synthetic oils run cooler than conventional. In the early days, mechanics that didn't understand the difference between the internal friction of the oil itself versus friction between the moving parts of the engine, assumed synthetics decreased the latter and that was why the syn oil was running cooler.

 

I agree - nothing scientific to back this up but when I ran Syn3 (20/50) in the tranny, shifting was loud as hell. I personally think 20/50 is way too thin for a manual transmission.

Funny, but all of this oil technology is making us crazy trying to figure out which is "best". HD has been in business for over 100 years and synthetics have not been on the scene that long. The older bikes ran forever on dino oil if you took care of them. Maybe synthetics are needed because the new motors are larger and run hotter, who knows. Hell, I have been suckered into the synthetics game too but in reality I have not been able to tell the difference between the two types of oil (by noise), at least in the engine. For me it's the advertising about heat resistance, the fact I live in South Texas and a fairly long commute in heavy traffic that made me switch the motor to syn. No idea if it does any good or if my $10 a quart is going to waste...

Here's a thing: why the hell did the price of synthetic oil go up when oil prices did? Um...isn't it synthetic and not petroleum based?

 

The SAE viscosity scale for transmission and gear lubricants is not the same as for motor oil. A 75w90 gear oil is roughly the same viscosity as 10w40 motor oil.

The primary synthetic base oil, PAO, used by Mobil 1 is derived from ethylene gas, a byproduct of crude. Group III hydrocracked base oils are refined crude. Syn3 uses both PAO and Group III.