02-28-2017 09:25 PM
Cat does not recommend any commercial gas engine oil. Cat decided many years ago to have a branded oil that meets the Cat gas engine requirements so that a customer could obtain a good performing in any part of the world, where sometimes good performing commercial oils for gas engines is not available. Good performing commercial gas engine oils must meet a Cat designed 7,000 hour oil test that will allow a commercial oil supplier to prove that their brand of oil is an acceptable performer. The field results are shared with Cat engineers and the commercial company is free to advertise the oil performance results. However, Cat does not recommend any oil.
There are a lot of good performing gas engine oils available besides Cat gas oil. Mobil Pegasus 805 has been a good performing gas engine oil. Mobil also has 905 and 1005 available, with the major difference being in the base stock oil. There are many G3500 and G3600 engines running on Mobil Pegasus oil.
Since you have learned that another Cat gas engine seems to have the same blackish issue, let me suggest that you, for the sake of determining oil performance, why don't you try using Cat gas engine oil in this G3608 for a while and see if the blackening issue goes away. It would only cost a bit more for the oil but it would give you an alternative for comparison. I have seen this done by other customers with some satisfaction and resolution has occurred.
If you hae any questions, don't hesitate to contact me.
If you have
02-27-2017 04:54 PM
The prelube pump suction is a hose that runs from the inlet of the prelube pump down to a connector on the big tube that is the suction to the main oil pump. You could disconnect this from the prelube pump and use it to supply the prelube pump from a barrel or container. However, there is no manual shut off on the prelube pump suction line so the crankcase will have to be drained because all of the prelube suction line is below the crankcase level. Cat never installed a manual valve in the thoughts that someone might accidentally leave it closed.
You could connect another clean pump to the connection where the prelube pump discharges on the lube oil piping. This would feed oil into the engine passages. The prelube pump does not have near as much flow as the main oil pump so it will not flow to the upper parts of the engine very quickly. You also would want to be sure that there is no contamination from a separate container of oil.
02-27-2017 04:00 PM
At this point I'm pretty sure the oil turned black again becasue of the left over oil in the engine being diluted into the fresh oil. We are looking at ways to flush the oiling system.
If I'm correct it looked like the main oil pickup in the crankcase feeds both the pre-lube pump and the main oil pump. Is there a place where we could introduce the fresh oil to the pre-lube pump and use it to flush the engine without running the engine?
02-23-2017 10:39 PM
Dwight, I am at a loss as to what is making your oil black. It is a bit difficult for me to visualize what you have. I think of black oil like what you have in a diesel engine. The soot from combustion turns the oil black pretty quick. But gas engines don't produce soot from combustion so the oil stays a lot cleaner (lighter in color).
I just don't know what the source is. I don't think the color of the oil in itself is a problem but not knowing what is causing the darkening, I can't say that it does not contain something that is harmful to the engine. The oil samples look pretty good. I recommend that the TAN be watched so the oil doesn't get too acid. Of course, air/fuel ratio has an effect on nitration, which can cause some darkening as can oxidation. So these two observations are a check on engine setup and operation with regard to emissions and temperature.
The only other thing that I can consider is the remote possibility that someone has inadvertently connected a line or pipe incorrectly and this is feeding something into the engine lube oil that might be causin this discoloration. I just don't know.
02-22-2017 09:48 AM
I just got the oil analysis reports back. The old oil was drained, and the crankcase was wiped clean. No deposits were found in the crankcase. The filters were changed and no porblems were found with them. Of course you can't get all the oil out of the lines and heads, so once the new oil was run for 24 hours it again becomes the same color. The lab now explains that it is too dark for the particle analysis laser to pass through and that is why they can not do a particle count on the sample. We sent off three samples and they are:
1. As found
2. Fresh oil fron the storage tank
3. After 24 hours of run time
Is it worth the cost of the oil to flush the engine with clean oil? I think it would take two or three flushes, complete oil changes, in a row with very short run times between each to clean out the oil system.
01-31-2017 12:02 PM
I am glad to hear that the oil is being changed. Cleaning out the oil pan with careful inspection to see if there is any debris/foreign material in the bottom of the pan is important.
I probably would take an oil sample after a 24 hour engine operation. That should be enough to have everything in the oil system have full circulation to move any remaining sediment to the oil filter elements.
I wish you success. I am interested in what you find and what the success is.
01-31-2017 09:13 AM
Finally got word that operatioins is going to drain the oil and clean the crankcase out on Feb 8th. The engine is in an enclosed building and I should be able to stop by that afternoon to see what it looks like. At that same time a new dedicated oil sample line will be installed. It will beinteresting to see how long the oil stays clean and if a new sample taken maybe a week after the change shows any high levels of sediment. Do you think a week would be long enough or should it even be sampled a day after the new oil is in?