75w-90, where to send my sample for analysis???

J

jetman

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I have a 1996 Prevost bus/motorhome. It weighs 41k to 51k#s going down the road (65mph) depending upon what we're towing or not. Gross combined vehicle rating is 57k#s.

In June of 2014, when it had 67k miles, I changed the rear differential gear oil with 4.5 gals of Amsoil SVG 75w-90. Today it has 112k miles. I'm changing the gear oil again soon and want to know who best to send a sample to for analysis?

It's a Rockwell Intl 3 member, model A58 3200P1706, ratio 4.56
 
Yes, I know there are a lot of companies to send a sample off too. I've been using OAI, BS, & JG Lubricant services for 10+ yrs for oil, atf, and coolant. But I need someone who knows about gear oil results. What acceptable? whats not?

Anyone know of someone??
 
jetman said:
Yes, I know there are a lot of companies to send a sample off too. I've been using OAI, BS, & JG Lubricant services for 10+ yrs for oil, atf, and coolant. But I need someone who knows about gear oil results. What acceptable? whats not?

Anyone know of someone??
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@MolaKule Can you advise?
 
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Here it is gear oil analysis:

This gear oil is 9+ yrs old w/43k miles and the formulation has changed in the past 9 yrs, that is why the lab flagged Boron & Zinc. This ole formulation has a little more of each than today's formulation.

Manual Link: http://graphicvillage.org/meritor/MM1.pdf

In Meritor Maintenance manual 1 (MM1) "Preventative Maintenance and Lubrication", section1, states used oil analysis limits are:
Iron (FE): If the level is 1000-1500 ppm, resample the oil. If resampling indicates that the iron level is above 1000 ppm, drain and replace the oil. If the level is above 1500 ppm, drain and replace the oil.

Silicon (Si): If the level is greater than 100 ppm, drain and replace the oil.

Water (H2O): If the level is greater than 0.3%, drain and replace the oil.

Phosphorus (P): If the level is less than 900 ppm, it is possible that the oil is not a GL-5 gear oil. Contact the lubricant manufacturer or Meritor Materials Engineering to determine the expected phosphorus level of a new oil sample. Only GL-5 type gear oils are approved for use in Meritor differentials.

I did change the gear oil, with 12 qts of Amsoil Long Life 75w-90 and 6 qts of their Severe Gear 75w-110

What say you? Iron? Aluminum? Silicon?

DSCN0717.JPG
 
?? Any BITOGers knowledgeable on the above differential UOA. @MolaKule

I did not send in a virgin sample I talked to OAI and Amsoil on the phone. I think I'll call Meritor and/or Blackstone next.
 
jetman said:
Here it is gear oil analysis:

This gear oil is 9+ yrs old w/43k miles and the formulation has changed in the past 9 yrs, that is why the lab flagged Boron & Zinc. This ole formulation has a little more of each than today's formulation.

Manual Link: http://graphicvillage.org/meritor/MM1.pdf

In Meritor Maintenance manual 1 (MM1) "Preventative Maintenance and Lubrication", section1, states used oil analysis limits are:
Iron (FE): If the level is 1000-1500 ppm, resample the oil. If resampling indicates that the iron level is above 1000 ppm, drain and replace the oil. If the level is above 1500 ppm, drain and replace the oil.

Silicon (Si): If the level is greater than 100 ppm, drain and replace the oil.
Click to expand...

I would still opt for a 75W110 for future use.
jetman said:
Water (H2O): If the level is greater than 0.3%, drain and replace the oil.

Phosphorus (P): If the level is less than 900 ppm, it is possible that the oil is not a GL-5 gear oil. Contact the lubricant manufacturer or Meritor Materials Engineering to determine the expected phosphorus level of a new oil sample. Only GL-5 type gear oils are approved for use in Meritor differentials.

I did change the gear oil, with 12 qts of Amsoil Long Life 75w-90 and 6 qts of their Severe Gear 75w-110

What say you? Iron? Aluminum? Silicon?

View attachment 126406
Click to expand...
I would say this analysis is about what I would expect for this mileage.

This differential does not appear to get much use so moisture accumulation can be a factor resulting in a milky oil when drained.

Silicon may come from a bad breather tube ingesting road dust or RTV sealant applied to the differential cover.

You may want to replace the breather tube for good measure.

One other comment: New multi-functional EP additives now being used may not show much phosphorus in future analysis, nor exhibit the odor of older formulations.
 
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MolaKule said:
I would still opt for a 75W110 for future use.
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1/3rd of what I put back in is 75w-110, the rest is 75w-90.
MolaKule said:
I would say this analysis is about what I would expect for this mileage.
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That's what Blackstone told me on the phone too.
MolaKule said:
This differential does not appear to get much use so moisture accumulation can be a factor resulting in a milky oil when drained.

Silicon may come from a bad breather tube ingesting road dust or RTV sealant applied to the differential cover.

You may want to replace the breather tube for good measure.
Click to expand...
Thanks @ MolaKule,

2 yrs ago I replaced both drive axle inner hub seals. I may have gone a little too crazy with the silicone.

When I drained the old gear oil out to change it and take this sample it was fairly clean and not milky looking at all. We live in the south and travel only in the warmer months. Our trips or usually 6 hrs plus in duration in the heat. I believe condensation evaporates when we travel. The uoa "water" is okay.

The breather is fine. I know because when I pulled the drain plug without pulling the fill plug first, I could hear the rush of air flowing thru the breather.

This is what the differential is in:
Prevost BR 3.28.20.JPG
 
117 ppm of Fe is very good for 43k miles. While I don't know about this specific diff, I've had some conversations with Jim Allen a few years back, and I can say that the wear rate is very good for an appplication such as this. Typically the highest wear in a diff is the first 1000 miles as the gears seat into each other. After that, the wear should be commensurate with the use. Futher, the wear totals are well below the Meritor established max limits; no risks there as well. Contamination is also low.

Assuming your operational patterns don't change much, I'd say your good for another 10 years.
 
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