: Blackstone on 5400 mile Diff oil



M5eater
10-27-11, 10:12 PM
When I changed the oil this past week, I noted the magnetic plug was covered.. I got a bit worried and sent a sample off to Blackstone hoping that if indeed it was wearing more than normal the analysis would backup my standing for chaining it.

The following is what they sent back tonight. Note that this oil had aprox 5,400 miles on it. There is no scheduled service for the diff that I'm aware of, and typical industry standard is 30-50K.

cruiser68
10-27-11, 11:06 PM
Makes me want to change mine this weekend at 7500 miles. I LOVE Blackstone Labs. I've been using them for over 10 years for engine oil analysis.

MrMaschine
10-28-11, 12:03 AM
Had mine changed yesterday at 23k miles. all i can say is OMG the smell had to be the worst ever of any fluid drained from a gear case in my life. It smelled so bad you could smell it across a busy street across from the shop. Brutal.

Oil was like water viscosity and BLACK.

now my rear end isnt making the groaning sound anymore with the new Mobil1

M5eater
10-28-11, 07:08 PM
I will admit, i've not see gear oil this black in such a short time, nor have I experienced one with such a strong odor, hence the analysis, and thus my mind is more at ease.

FLTRI
10-28-11, 07:16 PM
Okay, you guys got me hand-wringing about the rear diff now... Can anyone point me to the required lube, additives if required, and amounts???

Thanks!

Speedtrapped
10-28-11, 07:23 PM
I used Redline 75/90, and went to caddy dealer and bought the additive. Changed mine after 1k. It stank, was black, and plug was covered with griity gunk

lilred
10-28-11, 10:14 PM
I will admit, i've not see gear oil this black in such a short time, nor have I experienced one with such a strong odor, hence the analysis, and thus my mind is more at ease.

What fluid did you replace the stock fluid with?

cruiser68
10-29-11, 03:50 PM
I just changed mine today after reading this post. I am very happy to report mine was not bad at all. Stunk real bad. However, the fluid was dark but not nasty. Real slippery with no grit when you rub it between your fingers. The magnet had the more typical 1/8 inch of fuzz. So I am pretty happy. I am at a little over 8000 miles with a good track day on the road course. Looked good enough I'm not sending it out for analysis.

I went with Amsoil Severe Gear Lube (75/90) and 2.4oz of Amsoil limited slip additive. Seems quiet so far.

M5eater
10-29-11, 05:16 PM
What fluid did you replace the stock fluid with?

1.3-1.4quarts Mobil 1 75W90 LS, 2oz and some change worth of diff additive.