Alternatives to RockShox Oil, Redrum, etc?

[Xteife]

According to their site:

Can I use non-suspension oil or other hydraulic fluid in my fork?
No. It must be suspension oil. Our proprietary fork oil is a special blend engineered to give your fork a superior ride.

I find it hard to believe that there is no alternative. Does anyone know something I don't?

What about for Redrum?

Just trying to save a buck... Thanks.

[scout]

Any motorcycle shop will have fork oil of different manufacturers and in larger amounts, be sure you get the correct wieght. But really, how much do you change the oil in your fork and do you want to void the warranty on an expensive fork? I don't know what fork you have but if it is newer and has the Rockshox proprietery coating on the stanchions I would be real careful about what you use.

[Xteife]

I'd change it more often if it was cheaper. I don't recall seeing anything about voiding the warranty if the wrong oil is used, but I'll double check. I'm pretty sure it's a 2001 SID XC...