8 1/4 Rear End - Drain, Clean and Refill?

[Glennster]

I 'd like to get some fresh oil in my old 8 1/4 rear end. My plan was to pull the rear plate, blast the gears and everything in there with my favorite cleaner (starter fluid) to get rid of all the sludge that's in there.
Then, fill her up with the proper gear oil. Once again I come to the experts for some help.
1. Is this a sound plan of attack? If not, please tell me ..............
2 What's the best oil to use in there? Synthetic?

Thanks!

[nivvy]

Dr Diff recommends Supertech 85w140...... walmart stocks it also......... 

thats what im putting in my dana 60 

[Chryco Psycho]

sounds ok , either 80-90 gear oil or 75-90 synthetic

[Glennster]

I hear that synthetic tends to leak where dino oil will not, could that be an issue with my old rear end?
I run synthetic in my 2002 Honda 1800cc V-Twin motor and rear gears, this bike shifted with a big clunk UNTIL, I went synthetic..................

[71chally416]

Only used the syn lube once in 35 years, and the rear broke behind a weak motor. Never again. 

[Glennster]

How could the Synthetic lube have caused that?

[Chryco Psycho]

I have had no issues with synthetic , but I don`t put a lot of miles on my cars either

[71chally416]

How could the Synthetic lube have caused that?

Don't know. The rear somehow survived since 1969 with regular gear lube. It was a 3.91 OEM out of a Superbee. Started making a clicking noise with the old 360 my car came with and when I pulled it out....

[71chally416]

The lube probably had nothing to do with the failure, but I've never broke a rear gear with such a weak motor. I'm not using it anymore.