Well here's what I have found, after trying different oil's in my front end, I have found the easiest steering to be Mobil 1 synthetic gear lube, It's a 75w-90 but is equal to 20-50 auto oil in viscosity, I got it at Autozone for $6.99 a quart, why is it better? well first it's $1.00 cheaper than the 20-50 v-twin, and second it's made for gears and diff's, when you take the cap off and smell it you will see waht I'm talking about, you can smell the loads of extra zinc and phosforous that is put in gear oil's for extra wear protection, and all the extra anti-wear ingrediants taht are not found in auto or motorcycle oil's, I put it in and it steers like a dream and the 4x4 works smoother too, pulling the diff lock lever makes the front end lock just as much as with petro oil. but it does not fight you by jerking back and forth, It just flat out make my front end work better and steer easier. Makes since really it is what this product is designed to do, engine oil was never designed for differential's....try it the next time you change your front diff, and if it isn't what I claimed it was, fell free to come back on here and cuss me out...

 

Cuss you out? You are right on the money with that oil. You made my point. I think I am gonna try that exact oil you are using. I want a little more diff stiffness than I have with 20w50 synth.

However, when I was using 20w50 dino oil, it was OK in the front diff until the weather got nasty cold, and then it was so stiff it was hard to ride. Synthetic is going to stay more consistent and not make your steering too hard.

 

Nyroc I just dont understand why you're searching for oils with thicker and thicker weights/high heat protection, when you originally said the front diff doesn't get as hot as the engine. You also experienced heavy steering at cold temps with dino because 20w-50 is too thick. Synthetic has better cold flow properties so it worked in your case, but why are you searching for such thick oils? Did your steering feel too loose/easy?

 

To be honest, I never noticed a difference ineither of the 2 lubes I have tried. Guess I'll try STAKK'S wonder-lube, too. I just don't use my locker much. I go 'round those big $hitholes! Don't like the wear and maintenance aspect of "mud-daubing". YES, my friends call me a pu$$ sometimes, BUT my bike runs when a lot of their's are in the shop!

 

Everyone makes very good points. I have had problems in the past with synthetic lubricants (mobile1) not playing well with clutches in street bikes. I have not disassembled the front diff on the prairie but wonder if it contains a clutch (disks) which are simular to a regular clutch. No doubt as to the efficiency of synthetics but wonder if an organic oil may not be the answer in this application. One of the biggest weaknesses of organic based oils is the acids/breakdown which occurs when exposed to the unavoidable extreme heat and blowby created by the engine. (which wouldn't apply in the case of the front diff) The shear-strength rating probably are different organic vs synthetic vs gear oil but would guess a gear lube's shear-strength would be superior than engine oil. Mine still has the factory stuff in it but need to figure out what I'll dump in it when the time comes.