What service interval are you using to change the transfer case and differential lube?

 

Whenever I remember. No, but seriously around 50k miles.

But this time around I used Royal Purple and after seeing some studies on gear oil, I want to get that stuff out of there. So I'm thinking a 30k-35k run this time, will change it out next summer (currently have 21k on the gear oil). No time left to do it this summer.

 

I just changed using Amsoil---I think we read the same information that raised some red-flags on the Royal Purple. Thank you for the information. Does Lexus have a recommended service interval as I have been unable to find one.

 

What "red flags"??? I've been using RP for the last 25,000 miles and don't see any problem with it. But of course I haven't taken apart the rear diff or transfer case and looked at it under a microscope either. So please explain. And obviously all our RX's are over 10 years old already...so how much does it REALLY matter any way? Just askin.

 

Apparently testing was done on the various gear lubes and Royal Purple's test results were marginal regarding it holding its viscosity, etc. One report on the subject can be viewed here Does this mean your differential or transfer case are going to implode, I don't think so, but perhaps it may impact a decision on how long you leave that lube in your car.

 

Thanks much for the info. Will definitely read it.

 

WOW! Was very UN-impressed with the results of the Royal Purple! I think I WILL change it out for some Amsoil Severe gear oil!! Even tho the RX is 12 years old (125,000miles)I do still think that RP gear lube can still be counter productive and even destructive...based on that test I read. Thanks again for the info.
P.S. The only thing I would add tho is that that test appears to be from 2007. I would imagine RP has vastly improved their product in the last 7 years...at least I would hope so.