I’m doing the 1000 mile service on my 2008 Fat Bob; it’s my first bike so my knowledge is low.

What is better synthetic or non and does synthetic effect the warranty?

What is a good brand and weight for the trans and primary? Are they the same fluid.

 

You will get umlimited answers, here's my experience.

I switched to Mobil 1 VTwin synthetic after 3,000 miles, have had great luck with Mobil 1 in my other vehicles. I switched to Redline VTwin Shockproof in the transmission. Both have a big following here.
I have not tried anything new in the primary besides the Harley dino.

My experience, I can tell no difference in the "feel" of the bike as far as shift noises or quietness. Without a thermometer, I can discern no difference in the heat.

My guess is that designer lubes are a waste of money and a regular change will make more difference with the stock oils. I am prepared for the flames.

B

 

just did all three holes on my 07 street bob i may consider doing synthetic after 5000 miles but i went with dino
valvoline 20w50 in the crank
the primary used shell rotella 15w40
and for the transmission since it will be in the hundreds soon
i went with a valvoline 85 w 140 gear oil

i must say this combination worked fantastically the bike runs like hell on wheels
freebyrd

 

I went with the Amsoil Severe Gear in the tranny, (07 FXD) it totally eliminated the 5th gear noise (the helical cut gear ) I'm sold on the syn products Just don't use syn in the primary (toooooooooo slippery) Just returned home from an 700mi weekend ride trouble free too

Just my .02 worth
D/C

 

I've been running Mobil 1 75-90 in the tranny with good results. I had been running HD Formula + in the tranny and chaincase for several thousand miles with no problems except when it gets hot in the summer (South Texas), shifting is noisy. After the switch, shifting is quiet all the time, no matter what temp it is. I have stuck to F+ in the chaincase because it works fine. Might switch to a regular dino oil, but not sure what weight to run. The only reason I want to switch from F+ in the chaincase is it's expensive, and I am not even sure what the hell it is...it's thick, but HD won't fess up the viscosity, or whether it's dino, syn, or what. I figure I can get a high quality dino oil for $2-3 a quart that will do just fine.

As others have mentioned, I have had issues with syn in the chaincase - my clutch tends to "grab" when I run syn there, so switched back to dino.

 

what weight dino do you use in the primary, i have hear good tough things about the rotella diesel oil and i always use heavy wieghts in the summer, its cool in california this weekend but hundred degree weather is coming, and that heavy tranny fluid is going to do a great job,
since my service it seems like i got a dozen extra horse power and my primary shifts like butter the clutch seems to have just about the rigth amount of play and grabs about halfway from releasing it which seems about right
freebyrd

 

dymamite 17 do you know all the position of the drain wholes? and the torque specs? the primary cover was the bitch for me,
they didn't sell me the frisbee gasket from the dealership which is what i needed so i reused the frisbee bike only has 2800 miles on it,
and the primary must be filled with the bike standing up level,
i had to do a trick with a 2x4 and a bottle jack, don't ask? but it was level

does your fat bob have the 96inch and the six speed?

 

freebyrd - I use HD Formula + in the primary but am interested in using another oil for several reasons. I believe F+ is a dino, but it's thick, really thick, like 50 weight or so. What weight rotella you use in the primary 15/40? Is that just a regular sae motor oil, or a diesel engine oil?

 

yes it is for deisel applications some of the toughest 10/40 on the market and won't break the bank 2.88 a quart at wally world
freebyrd

 

I have been running HD Shockproof in the tran, just changed out after 5000 and what a waste, should have lft it alone, it still looked just like it came out of the bottle and NO shavings on the magnet/plug. I have been using redline primary but Im going to change that out again with dino next chang-lots of shavings.
I was running 20-50 Royal Purple in crank, it change out ok, looked good, no shavings, but it sounded like a loose bucket of bolts.
I changed crank to 60w Valvoline racing and some lucas oil stabilizer, all the top end noise went away. I run a PCIII to cool the motor and I rode around in 101 temp saterday with no heat issues so Im running dino in the crank this 3000 and if what I feel now is tru no more syn for me. Dino 3.39qt, RP 10qt or 7.50 20-50 that doesnt say motorcycle on it.