Not sure. At what point should I change the final drive oils? Is it something I should do now or every two years?

 

What machine do you have?

Anyway, doing it at 2 years would be fine. Lots of people neglect doing it at all.

If you wanted to, it wouldn't do any harm to do it on the break in service. It takes such a small volume of oil, the cost is practically nothing.

Personally I run 75-90 Redline GL-5 full synthetic.

 

I do mine initially after about 5 hours of break-in riding. This is to quickly get out any metal shavings that might be leftover from machining.

After that I do it twice a year. Why so often???? If something like shavings were to show up in the oil, why in the world would you want to wait 2 long years to find out about it....and it is so simple anyway!

What I run: http://www.maximausa.com/products/ge...thgearlube.asp

 

i also dump mine yearly, it holds shockingly little oil. I just changed the diff oil in my friends powerstroke F350 since he always carrys to much weight like a 12' camper on the bed while pulling a 26' enclosed trailer filled with hay with a jeep inside.
when i dumped his oil it looked like silver metalic paint, i then grabbed a large magnent and held it near the side of the drain pan. the oil moved towards the magnent there was so much metal in it!

 

My truck also specifies a 15k change on the dif oil, and requires synthetic. 11.5 aam holds quite a bit of oil, and it gets pricy.

 

Thanks for all the info. Any input on Royal Purple gear oils?

 

ReconRanger is the oil expert here, so I'd defer to him.

Personally, Redline or Maxim would be my top pics.

 

Royal Purple appears to be PAO based, fortified with some ester. Redline and Maxima are ester based, with some PAO thrown in for "balance". The former is good, the later is even better.....

With gear oils, the high-pressure additive package is all important!