Thanks for posting. Always like looking at this type of stuff

 

Good stuff BirdShot, as usual. If you want to go for greatness, try flushing the diff (it's easy with our set-up) and switch to LE 1605. Here are some instructions from Mag-Hytec:


http://www.mag-hytec.com/oil-1605DUOLEC.htm



Their DUOLEC AW/EP additive will not show up on a UOA. Good luck.

 

This is an interesting thought.
But.. the hypoid gears don't mesh together like straight or diagonally cut gears, they slide more into eachother.
And the mesh area is submerged in oil.
Still, it could be that thicker oil will create some cavitation (known in pumps), when the gears move faster then the oil can flow into the gap the gears creates.
Cavitation can also damage pump vanes and housings so it is a powerfull phenomenon and it happens with water, we all know water is pretty thin (1 cSt) so with thicker fluids it will happen for sure.
IMO the sliding is what the oil has to deal with most though, sliding under force.
What oil is relatively thin with a high EP?
Do they exist?

Long time ago I found a review of LE-607 with the solid additive.
They used and compared it with several other oils in a 4x4 diff, with lower diff temps as the main result IIRC.
The temperature readings were done pretty accurate (can't find the link, its over 4 years ago)
Less friction = less heat.

Did you look at the ring gear through the drain hole?
Its a bit tricky with (hot) oil dripping down, but if you take the time and let the diff drain you can see the contact patch on both sides of the ring gear.
Not easy (impossible without borescope stuff) to take pictures.


Thanks for posting this thorough UOA!

 

I think this is the article written by Jim Allen Spifire mentions that offers some good documentation on gear oils:

http://www.fourwheeler.com/techartic...d_towing_axle/


You may have to refresh the link to get past the advertisement in order to read the article. LE 607 SAE 90 is the equivalent of LE 1605 SAE 110 wrt viscosity. LE 607 has been discontinued and has been replaced by 1605.

 

Hey Jack, thanks for that info on the LE1605's additive package not showing up on UOA's, that is good to know. I didn't realize that 1605 was SAE 110, it's been a while since I looked at a bottle of it.
Did you once tell me that LE1605's additive package promotes metal clinging and climbing properties ?.

I won't be able to do a UOA until the end of the summer driving season this year, I've run it for one season thusfar.

 

1605 contains a shear stable tackifier.

DUOLEC is a heat activated dual purpose liquid additive (EP/AW). It contains no solids. The reason 607 was discontinued is because the Almasol additive could be filtered out. It was a solid. You'll like the 1605. I think it's an improvement on wear protection, runs cleaner and cooler than 607.

 

thanks for the info birdshot, those pics of the diff oil smears are pretty scary to look at, do you notice any weird sounds during cruising/accelerating? How many launches do you think you've done on that run interval?

 

Thanks Jack !, great info as always.

 

Interesting stuff.
I noticed the last time I changed my diff fluid (a quick change after the break-in) I was still seeing more gunk than I would normally expect in comparison to what I used to see in my previous diff (well after break-in, after a long time of use) during standard fluid changes.
I think JFUSION's point about the Amsoil cleaning out older gunk actually goes beyond simply loosening and cleaning the old gunk in the diff. I believe the old wear particles and gunk that was loosened by the first fill of Amsoil in themselves created all sorts of NEW wear. And wear begets wear. The old wear particles would also account for the high levels of corrosion-laiden wear particles evident in the diff. fluid as well. Additionally, correct me if I am wrong - but if there was a lot of gunk in the diff to contend with - the additive package would get punished and not last a normal drain interval. On top of all of that - your car saw some serious track duty as well.

In all, I wouldn't jump ship based on your initial result. I know it's not cheap, but I recommend you drain and fill again with SG 75W110 and change after a short interval. I think after a thorough flush it would provide a more realistic example of what the gear oil has to offer. If you changed to another gear oil you would basically be giving the new gear oil a free pass on the back of the work the SG did cleaning that diff for you.

I'll post my next sample here shortly (changing the fluid this week). Lots of hard street driving on this pending sample, including a couple long road trips. No track time on this sample though. A good amount of street use, back road fun, and quite a lot of 'reasonable' street launches. This sample will have about 12,000 miles of use on the clock. More than I usually go on a diff fluid change. I suspect there is a little more break-in on this sample - we will see.

 

Im also about to send in a sample of my 15,000 miles LE 1605. Lost of 9k shifting, racing, a few donuts here and there.. Stay tuned!!