Final Drive Oil Analysis

[JfitzCat]

Hi Guys, long time lurker, first time poster. I bought a certified used 2018 304e2 with 2000hrs from Cat about a year ago. This machine was Maintained by Cat from new, always on schedule and had oil analysis done at every service. So when I got it it had probably 8 samples done from each compartment between 2018-2023. Engine an Hydraulics look great. Final drives not so much. For the first 1200hrs or so they were changing the oil in the drives every 300-400hrs. And everything looked great. Then I guess theu decided to follow the manual and go 1000hrs on the oil without changing. It’s insane that this is Cats recommendation. They hold barely a half quart, roughly $8 worth of oil if you buy it from Cat. But I digress. Ever since that sample all subsequent samples have not been good. High iron, and chromium
, and high levels of oxidation.

My SOS advisor said the machine should be brought in to cat for inspection. It’s under warranty anyways. They pulled the covers off the finals and said everything looked great. Gears looked good. I assume there wasn’t any play suggesting bearing problems. They flushed out the drives to hopefully get out any residual metal from that long service interval. I pulled a sample 77hrs later when I was doing my yearly service and still iron was high, as was oxidation.

This whole time I been running Lucas 75w140, as that’s what cat sells you and the parts guy says it’s the only oil indicated for this machine. The service department uses the same oil. My SOS advisor thought that oil may be too thick for my climate. Not sure about that, I’m in Nc so it’s very hot. But she suggested I try 30wt TODO, which is TO-4 spec oil. So I flushed the drives again using Diesel and refilled with 30wt TODO. I’ve been doing some research since then and 30wt seems pretty thin. There isn’t really even a comparable SAE viscosity for the 140 gear I’ve been runnng. 90wt gear oil is like 50wt SAE. I guess 30wt is like 80wt gear oil. Seems like the recommendation is typically a 50wt TO-4 oil for final drives.

What do you guys think? I want to get the wear metals back to normal, if that’s possible. Or atleast get them wearing at a slower rate. I’ll probably pull a sample at 50hrs and see how things look. When cat had it in for inspection they pulled a sample on the oil that had been in there for just 16hrs and everything was elevated. So 50hrs should be plenty after the flush to get a good idea if this 30wt to-4 oil is doing a better job. I’ve attached the latest oil analysis on both drives. I appreciate any insight you guys can provide.

 

[James Sorochan]

Your numbers don't look that bad to me. I would change the oil more often if that makes you more comfortable. Moving up to 50W TO-4 might be ok if the dealers agrees. One thing I notice is the oil additives in the last two samples like zinc and phosphorus are not depleted so that's good. I think Nige might have something to say on this topic.

 

[Nige]

Can you post a Serial Number so I can look at the O&M fluid recommendations for the final drives.
EDIT: It was on the oil analysis report. So confirmed that CAT Synthetic GO is what's called for in those mini-ex finals.

The one issue with a machine this small is that without a complete disassembly and cleaning of all the parts in a parts washer contamination from the oil that was in it previously will hang around like a bad smell. It may take a while to get things back to "normal", whatever that is.

It's interesting that there are significant amounts of silicon (aka dirt) in the analysed samples. Increased silicon will cause increased iron (and other metals) - you can see it right there in the analysis results.
That could suggest that cleaning of packed dirt/mud around the floating seals of the final drives may not have been the best. Take care to do this cleaning on a regular basis. It should be done at least daily and probably more often if the ground conditions require it.

TBH I think that it won't matter too much what oil you put in it, if you don't stop the dirt getting into the compartment any oil will suffer, especially considering that there is only 1 litre of oil in each final drive.

 

[JfitzCat]

Can you post a Serial Number so I can look at the O&M fluid recommendations for the final drives.
EDIT: It was on the oil analysis report. So confirmed that CAT Synthetic GO is what's called for in those mini-ex finals.

The one issue with a machine this small is that without a complete disassembly and cleaning of all the parts in a parts washer contamination from the oil that was in it previously will hang around like a bad smell. It may take a while to get things back to "normal", whatever that is.

It's interesting that there are significant amounts of silicon (aka dirt) in the analysed samples. Increased silicon will cause increased iron (and other metals) - you can see it right there in the analysis results.
That could suggest that cleaning of packed dirt/mud around the floating seals of the final drives may not have been the best. Take care to do this cleaning on a regular basis. It should be done at least daily and probably more often if the ground conditions require it.

TBH I think that it won't matter too much what oil you put in it, if you don't stop the dirt getting into the compartment any oil will suffer, especially considering that there is only 1 litre of oil in each final drive.

Thanks Nige. So cat Synthetic GO is the 75w-140. Im taking a huge step down in viscosity with 30wt TO-4. But that’s what the advisor recommends so will see how it does. I think 50wt TO-4 would have been the better choice.

Regarding the silicon, the oil tested with 1000+hrs on it had 49ppm. The next test when I owned it with 117hrs also had the same. But the next two weren’t bad. Most recent with 77hrs had 12ppm. That doesn’t seem too bad?

But also, how do we know that’s dirt Entry and not an additive for anti foaming? It’s looks to me that 2 different kinds of oil was used in these drives. The kinematic viscosity of the 10/22 and 5/23 tests were around 13-16, which would seem to be around 50wt oil. It had the exact same amount of silicon in both of those samples, 49ppm, and oil was changed between the tests. Then the June and Nov 2023 tests viscosity was 24-26, which was the 75w140. And silicon was 12 both times. Seems like too much of a coincidence to me? So it may not be dirt entry, but the Antifoaming additive used in those oil formulations?

I have no idea how it’s possible to clean out the area around the duo cone seal on these small machines.. I’ve looked at it a couple times now. It’s always packed. But there’s no room to reach in there behind the sprocket. I think the track would have to come off. You can’t reach it from the other side either. I had the cover off that protects the hydraulic side not long ago to clean that all out and you can’t see or touch where the seal is. I’ll have to see if I can fab up a tool to reach behind the sprocket.

 

[James Sorochan]

Clea .your tracks the best you can with a track shovel after every shift. Be careful when power washing as to not drive the dirt into the cone seal These machines have their advantages and disadvantages.

 

[JfitzCat]

Clea .your tracks the best you can with a track shovel after every shift. Be careful when power washing as to not drive the dirt into the cone seal These machines have their advantages and disadvantages.

I try to keep the the tracks cleaned out well. But man is the area behind the sprocket caked with hardened dirt. I gotta figure out a way to clean it out that doesn’t involve pulling the track.

Im definitely keeping the pressure washer away from them now. Think I might have got a little too close last time I washed the machine. When I drained the 140wt oil to flush and refill with the 30wt the left side drive either had water in it, or it was just foamy. I made the mistake of not pulling the level plug first before pulling the drain so I didn’t get to see if it was overfilled which would indicate water in it, since i know I put the correct amount of oil In it, filling till it ran out the level plug. But this is what the oil looked like. Hard to say if that’s milky or foamy/froathy. But I’m keeping an eye on that. Got about 17hrs on the 30wt oil so I’ll probably pull the level plug soon and make sure the oil looks good and isn’t milky.

 

[Nige]

From those photos the oil being drained is clearly heavily contaminated with water. If the water came from outside through the Duo-Cone seals as a result of pressure washing it would have obviously brought silicon/dirt in with it.

 

[Nige]

So cat Synthetic GO is the 75w-140. Im taking a huge step down in viscosity with 30wt TO-4.

Let's get the subject of viscosity out of the way first. See the illustration below.
The SAE30 TO-4, whose viscosity is measured on the SAE crankcase scale, is heavier when cold and somewhat lighter when hot than the 75W/140 that is measured on the SAE Gear scale.



TBH apart from these mini-ex machines and the tracked skid-steer product line EVERYTHING ELSE in the world of Cat uses TO-4/FDAO-specification oil in final drives. (This is most probably why you were recommended to switch oils by the dealer)

Until I looked for myself in a case a few months ago my first recommendation of oil for any Cat final drive would ALWAYS be a TO-4 product. The only reason I can come up with for the recommendation of a multigrade gear oil is the EXTREMELY small quantity of oil contained in these particular final drives.

 

[Nige]

But also, how do we know that’s dirt Entry and not an additive for anti foaming?

I've never seen silicon used as an additive in any type of oil I've come across while working with heavy mobile machinery. I have contacted a couple of people for their opinions but to me silicon always equals dirt entry.

The only potential caveat to the above is the possibility of it being used in some type of off-brand product or in a "snake oil" additive of some sort.

Edit: Have a sample of new oil analyzed. If there is no silicon present in the analysis you have your answer.

 

[Nige]

The kinematic viscosity of the 10/22 and 5/23 tests were around 13-16, which would seem to be around 50wt oil.

It could also have been an SAE90 gear oil. See the chart.

 

[Nige]

I have no idea how it’s possible to clean out the area around the duo cone seal on these small machines.. I’ve looked at it a couple times now. It’s always packed.

IMHO you are going to have to find a way to keep that area consistently clean without having to resort to pressure washing.

 

[Delmer]

Cat can only test what is in the sample bottle, and the sampling can vary enough that the 49 vs 12 is not really significant in the single digit place, call it 40 vs 10, pure coincidence that it was 49 twice and 12 twice. Two other samples from the same drain oil could easily have come back 35 and 55, or 6 and 20.

Notice everybody is saying to avoid PRESSURE washing, but you'll have to get the hardened dirt out of there so you can keep the seal area open to shed dirt instead of running in dust or mud. You're going to have to bite the bullet at some point and get it clean, and that's probably going to involve getting some water through the seal. A garden hose will rinse the dirt off eventually. Helps to start rinsing with the machine cold so you're not causing vacuum inside the compartment to suck water through the seal when the hot drive is cooled off by water, or even cools off from evaporation after you've washed it with hot water.

 

[IceHole]

I'm surprised they bothered to oil analize that. Cost of oil analize kit far exceeds the oil cost.

Change the oil and go on with things. It is what it is.

My machine had the factory oil in the finals with over 5000hrs and I've run into that often. Same with swing gearbox.

 

[JfitzCat]

I'm surprised they bothered to oil analize that. Cost of oil analize kit far exceeds the oil cost.

Change the oil and go on with things. It is what it is.

My machine had the factory oil in the finals with over 5000hrs and I've run into that often. Same with swing gearbox.

Lol, ya, when I buy the gallon of TO-4 it costs $2.75 per side to change the oil. Or $17 to sample each drive. But the purpose is to get an idea of the health of the drive. It’s a $3000-5000 part so $17 is minimal.

 

[Coaldust]

Analysis paralysis is a thing.
I’m having difficulty opening the reports on my iPhone for some reason. Nige asked me to chime in.

Abnormal silicon levels with fresh gear lube does cause alarm. Most PAO synthetic lubes have up to 24ppm si in the additive package. It’s important to sample the new oil, too. If the lab doesn’t already have the data on record. Various blenders also add si to value-priced conventional gear lubes as an anti-foaming agent in the 5-10ppm range.

If that was my machine, I would flush the finals with diesel and start over fresh. I would also think about how you are taking the sample. Suction gun, warm oil, contamination control, etc.

 

[Nige]

Lol, ya, when I buy the gallon of TO-4 it costs $2.75 per side to change the oil. Or $17 to sample each drive. But the purpose is to get an idea of the health of the drive. It’s a $3000-5000 part so $17 is minimal.

Try closer to $10k.
Oil analysis is one of your best insurance policies, along with using quality lubricants & filters.

 

[James Sorochan]

Some dirt up in around the final drive typically shrinks as it dry's out pulling away from the crevice. I agree with the last two posts.

 

[JfitzCat]

Analysis paralysis is a thing.
I’m having difficulty opening the reports on my iPhone for some reason. Nige asked me to chime in.

Abnormal silicon levels with fresh gear lube does cause alarm. Most PAO synthetic lubes have up to 24ppm si in the additive package. It’s important to sample the new oil, too. If the lab doesn’t already have the data on record. Various blenders also add si to value-priced conventional gear lubes as an anti-foaming agent in the 5-10ppm range.

If that was my machine, I would flush the finals with diesel and start over fresh. I would also think about how you are taking the sample. Suction gun, warm oil, contamination control, etc.

So the 12ppm in my last 2 samples isn’t necessarily dirt entry, it’s just the additive package. The silicon levels didn’t worry me too much. More so the high levels of iron, which indicates gear wear, and oxidation which could mean overheating.

That’s what I did 17hrs ago. Drained, flushed with diesel an refilled with new cat TO-4. So I’ll pull a new sample around 50hrs. They were also flushed around 100hrs ago by cat when they took that same in June of 2023. Was hoping everything would look good after that but the next sample in nov 2023 wasn’t very good. The fluids Been changed 5 times and flushed twice since that 1000hr drain interval. Hoping the next one after this flush will look better.

The only way I can pull a sample is with the drain plug. These drives are small so there isn’t room to put the suction hose in and turn it before it hits a gear. I get them warm before I pull the sample. I wait for a some oil to run out then put my vial under and collect it. After cleaning the cover on the final really well.

 

[Nige]

So the 12ppm in my last 2 samples isn’t necessarily dirt entry, it’s just the additive package.

I would suggest confirmation of that from an analysis of new oil, or ask your local Lucas oil rep.

Certainly the TO-4 SAE30 oil you are using now has no silicon in the additive package. It will be interesting to see what happens to the silicon levels subsequent to the change of oil type.

 

[JfitzCat]

I would suggest confirmation of that from an analysis of new oil, or ask your local Lucas oil rep.

Certainly the TO-4 SAE30 oil you are using now has no silicon in the additive package. It will be interesting to see what happens to the silicon levels subsequent to the change of oil type.

I can ask my monitoring advisor. She had a virgin sample of Cat hydo advanced 10 when I asked. Or ya maybe Lucas does. Do you think Lucas makes the cat synthetic GO? I thought Mobil made all their oils.

Will see how the next test looks. I feel like should be running 50wt TO-4. That’s similar in viscosity to 90wt gear oil, which is the lowest viscosity oil the manual recommends for this machine. But I’m in a warm climate, rarely below 32 and half the year is over 80 so there really shouldn’t have been any problems with the 75w140. If these next samples don’t show improvement I’ll either try some 50wt TO-4, or ditch cat oil all together and try some amsoil severe duty 75w90.