I changed the final drive oil in my Cat D3G (2200 hours on the machine). The oil was dark. I did not take a sample so I am just going by sight. It was sampled about 500 hours ago and the sample came back ok. The inside drain plugs are magnetized and there was some material attached to them. It was extremely fine like a paste and the color of anti-seize lubricant (a gray paste). The inside plugs had never been removed and were hard to get out. The paint was not even broken. The oil had never been changed based on the inside plug not being removed previously. If it was, it was only by draining the outside plug which would have left about two gallons of old oil in the drive. My question is, do I need to worry about the paste that was attached to the inside plug? There were no particles of metal just the paste.
No worries, that is normal.
If there were no particles of metal on the plug that were visible to the naked eye, then the paste to which you refer would be classed as normal wear. It's a shame you didn't send a sample of the dark oil that you drained for analysis, just for confirmation. I would have guessed it would come back saying that they could not do a particle count on it because of the dark colour, but hopefully the rest of the sample would have analyzed out OK. Unfortunately you'll never know. Did you flush out the final drive with a few gallons of new oil to wash all traces of the oil oil out..? Do you recall what the colour was like when the oil was sampled 500 hours ago ..? Did the analysis include a particle count and if so what was the ISO Cleanliness Code..? Personally I would pull samples off it every 500 hours in the future to get an idea of the wear trend in the compartment. You changed the oil at around 2000 hours, how much was that time-wise..? Without knowing how rapidly you are accumulating hours onthe machine maybe you need to be changing oil based on time rather than hours. Isn't 2000 hours classed as the equivalent of 1 year ..? What brand & type of oil are you using now..?
I used Cat TDTO SAE 50. That is for a temperature range (degrees F) of 32 min to 122 max. I was puzzled by the temp range. I could see using the dozer at around 32 degrees. The other option was SAE 30 but it has a max of only 77 degrees and I know I use my dozer at close to 100. So I went with SAE 50. There were definitely no particles. As I recall, it was fairly clean at the time of sample. I did not flush. Thanks for the replies, they are always helpful and I appreciate the time people spend helping those of us who need it.
The ambient temperature range is really designed to be used when the machine is are subject to a cold start every morning. For "continuous" operations like mining where the oil never gets cold you can actually go with a heavier oil than the table suggests. I would definitely look at how many hours you're working and if necessary change oils based on calendar months rather than operating hours. The final drive oil should be changed every 2000 hours or 1 year, whichever comes first. Nothing wrong with Cat TDTO SAE 50. It 's a good oil. In your case if you are starting work in winter with a machine that has stood all might and is therefore totally cold at an ambient temperature around the bottom end of the scale (32F in your case) take care to warm the machine up well to get the oils in all the compartments flowing well before you really put some load on it. Once the oils are warm you will have no issue whatever the ambient temperature might be.
Hey, Nige, that makes sense. Thanks.
Final drives take a load like you would never believe. I would change the oil at least annually but I would not let it get over 1500 hrs ever, and your wear is normal