I have in my sprinter a standard S-series which has travelled 290,000k's and whines like no tomorrow. Its not locked, nor is it going to be but I was wondering if anybody had any ideas on how to make it a little quieter, not after whisper quiet because that's not going to happen unless I get a new crown and pinion.

Just interested in whether or not anybody had some good oil mixtures or something of that order to make it better?

And I already know of the banana trick, I'm just after something which will last a little longer.

Another random interest question, I have read that some rt81 Corona's may have 3.7 ratio s series. Can anybody confirm?