I have read too many thread transfer case oil recommendation, but yet to hear from a someone claiming he/she had no issue substituting, say, Redline GL-5 oil (75W90) for the Audi's overpriced G 055 145 A2 oil.

So my question is, has anybody used a GL-5 rated oil in their transfer case without any issues?

I am thinking is that any GL-5 spec oil should have the same viscosity across the defined temperature range, allowing the quattro system to perform as intended. Plus the new GL-5 oil do not harm brass...


Thanks

 

What year and what model is the car? Most of the older cars (before 1998) don't really care what you put in them, as long as it's of the right viscosity. Audi just recommends their oil so they can overcharge you for it. You should be fine with the GL-5 oil.