Limited slip Differenical oil
 

I have a 1997 light duty 250 with 112,000 miles. I have amsoil in the l/s diff. It has started to chatter a little bit on hard turns I was thinking about changing the oil and using royal purple since it is more avalible . Will this cause any problems? I pull a 30 foot TT.

Did you add friction modifier to the oil? Apparently not adding it can cause the clutch plates to grab which may be your chatter noise.

yes i used the friction modifer from ford.

Did the clutch plates in the diff look ok when you changed the fluid or was there any sediment in the oil from disintegrating clutch plates?

I'm not sure what else it could be. Are you using 80W90? The 90w140 or whatever ford recommends is apparently crap according to Ford Mechanics who think it doesn't absorb water and leads to rust inside the diff housing. Not sure about that tidbit though.

Don't know what else it could be then.

since I have changed the oil everything is fine. What I was asking is replacing the amsoil with royal purple is that a problem and is the royal purple equal to the amsoil? Another words is synthic oil basicly the same reguardless what the brand