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Amsoil 75w90, 30K, 04 Chevy Tahoe #3217917
12/15/13 10:45 PM
12/15/13 10:45 PM
Joined: Aug 2011
Posts: 256
dhellman12 Offline OP
dhellman12  Offline OP

Joined: Aug 2011
Posts: 256
Oil was drained and replaced with another round of Amsoil SVG at time of sample. Nice to have a starting point since the first was the flush from the previous owner with unknown mileage/history.

Make/Model: GM Differential (Front)
Vehicle: 2004 Chevrolet Tahoe
OIL             Amsoil 75w90	Unknown
MILES IN USE    29,386		Unknown
MILES ON UNIT   158K		123K
SAMPLE TAKEN    11/8/13		5/3/11		
MAKE UP OIL	0		0		

IRON		133		346		
COPPER		5		8		
LEAD		1		1		
TIN		0		0		
NICKEL		2		4		
SILVER		1		0		
BORON		95		89		
SILICON		36		38		
SODIUM		2		4		
CALCIUM		12		80		
PHOSPHORUS	862		579		
ZINC		41		90		
BARIUM		0		1		
SUS @ 210F	78.6		56.0		
Visc @ 100C	15.16		9.07		
Flashpoint	415		370		
Water %		0.0		0.0		
Insolubles %	0.2		0.3
TAN		1.7		NA	

Oil Analysis Comments:
We're assuming this oil has been changed since the last sample, as wear metals and insolubles are reading a whole lot lower than last time. Nothing wrong with that. In fact, changing the oil has revealed excellent wear. This oil run is about as long as average, yet almost all wear metals are reading below average. We're not seeing any problems here. No moisture was found, and the viscosity was correct for a 75W/90 oil. The TAN was 1.7, showing little acidity in the oil. You could probably leave the next oil in 45,000 miles with no trouble. Check back then.

05 Kawasaki BF750 - 284hrs
12 Jeep 3.8L - Amsoil ASL 5w30 74K
04 DMax 6.6L - Amsoil AME 15w40 238K
00 WS6 5.7L - Amsoil ASL 5w30 256K
Re: Amsoil 75w90, 30K, 04 Chevy Tahoe [Re: dhellman12] #3218052
12/16/13 04:10 AM
12/16/13 04:10 AM
Joined: Dec 2013
Posts: 294
Dufus2 Offline
Dufus2  Offline

Joined: Dec 2013
Posts: 294
My (97) Tahoe was super low in the rear diff, had less than a quart in it when I bought it. Cleaned the magnet, added 8 oz MMO plus 2 qts of cheep gear oil from Autozone and drove it around for 1500 miles, mostly short trips. I did pull a trailer on a 200 mile trip without any issues.

The axle seals were wet and all the sludge buildup in the carrier had loosened up and was nearly gone thanks to the MMO. Replaced the outer seals and filled it up with FGR, I use that oil in all my vehicles as it is a very good gear oil from Amsoil... This is how I did my Differential flush.

If you do not know about FGR it's one of the first gear oils Amsoil made and its a premium GL5 75w90; unlike the marine GL4 or the 80w90 that is less expensive... Amsoil dealer since 1995

ASE Certified in Med/Heavy Truck Service including A9
Heavy Equipment Repair, Fleet Maintenance
Real Cars Rattle and Smoke a Little
Re: Amsoil 75w90, 30K, 04 Chevy Tahoe [Re: dhellman12] #3218143
12/16/13 08:17 AM
12/16/13 08:17 AM
Joined: Apr 2004
Posts: 764
Herndon, VA
btanchors Offline
btanchors  Offline

Joined: Apr 2004
Posts: 764
Herndon, VA
dhellman12 -

Excellent results! I'm presuming Blackstone did the analysis. TAN a bit puzzling, since two prior VOAs of SVG showed virgin TAN to be in the 2.5 range. I did see a VOA from Wearcheck for SVG that showed virgin TAN to be in the 1.5 range.

Re: Amsoil 75w90, 30K, 04 Chevy Tahoe [Re: dhellman12] #3218157
12/16/13 08:39 AM
12/16/13 08:39 AM
Joined: Nov 2009
Posts: 46
Calgary, Canada
ColdCanuk Offline
ColdCanuk  Offline

Joined: Nov 2009
Posts: 46
Calgary, Canada
Thanks cool to see an analysis on Amsoil SVG 75W90.

I've been using it in my diffs for years, obviously no problems.

I have taken note when people who know a lot more about fluids than me have said that Amsoil gear oils are pretty good.

Re: Amsoil 75w90, 30K, 04 Chevy Tahoe [Re: dhellman12] #3227037
12/25/13 08:02 AM
12/25/13 08:02 AM
Joined: May 2007
Posts: 7,981
Indianapolis, IN
dnewton3 Offline
Global Moderator
dnewton3  Offline
Global Moderator

Joined: May 2007
Posts: 7,981
Indianapolis, IN
Dumping an unknown fluid certainly helps understand a starting point, and gets out any "unknown" fluid that may not have been appropriate; you rarely know for POs do or why, but at times they can be careless or downright abusive. Dumping fluids when the maintenance routine is in question is never a bad thing.

The second UOA was a bit short; again, trying to see the condition of the diff. But if 30k miles was a planned distance, and not on a whim, then I'd have used any decent GL-5 dino lube; that distance is not far enough to really task a good fluid.

I'd run the OCI out to 90-100k for this round. The diff was broken in long, long ago. There is nothing but normal numbers here. The SVG is a stellar product; one of Amsoil's best offerings. Take advantage of it! 45k miles as Blackstone suggests is a waste; double+ that. It's not like a front diff on a Tahoe is seeing any kind of severe use after all.

Last edited by dnewton3; 12/25/13 08:05 AM.

The act of preventative maintenance, in and of itself, is FAR MORE important than brand/grade/base choices among lubes and filters.
- under maintaining something is akin to abuse/neglect; that can kill equipment by shortening the lifespan
- over maintaining something has never been proven to be anything but a waste of time and money
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