Generator engine oil question

[Barry Wolk]

I have a 20KW Koehler generator with a 4 cylinder Ford industrial engine almost identical to a Pinto engine. It's powered by natural gas. It runs at a steady rate of about 1500 rpm. It runs constantly when needed (5 days once) and runs every Saturday for about 45 minutes. That charges the battery and burns off any accumulation of moisture in the oil. Well, that's the intent. There is virtually no moisture as the engine block never gets cold. It has an engine block heater that keeps everything at about 110°, year round.

I use the same oil that I use in my old Porsche, Brad Penn with ZDDP in a 20w50. I change the oil in the Porsche seasonally or every 1000 miles and the oil is black, black, instead of the nice green color as it comes new. The oil in the generator is now two years old and has no trace of discoloration.

The manufacturer says an annual oil change is in order, but I can't imagine why. It's not like it burns gas or diesel, there's no carbon blow-by to speak of and far fewer corrosives than gasoline. The original oil came out after 5 years and only had a honey color to it.

Does anyone have any experience with engine oils used in this manner?

[Mad Scientist]

Natural gas burns way cleaner then regular gasoline. Thus there is little carbon to blow by the rings and contaminate the oil. The weekly running should keep the moisture under control. So if your oil looks clean that's because it probably is. I wouldn't bother changing it.

[Don Henschel]

And it's running unleaded fuel as well:rolleyes: Oh boy lets not go there again;) Moisture is not a problem on propane engines or natural gas, it's acid. You get alot of acid produced in propane engines resulting in corrosion. Natual gas is no exception and can be corrosive as well. It reminds me of a funny story. A guy I worked for many years ago ran propane equipment at his feedlot for cattle. The oil stayed crystal clear.He warned me about the acid content in the oil and used to check the oil by putting a drop on his tongue. If it "bit into his tonque" it was time to change. I got quite a laugh out of this but it's true. I tried this many years later when I used to work on fork lifts full time for a couple of years. Some of those fork lifts runnning hard 24/7 in the large warehouses would rack up 500-1000 hours on an oil change and would get overlooked for a service. It bites quite hard!;) By the way they didnt run 20w50, usually 10w30 or 15w40 with no additives and no problems. Almost all with typical flat tappet engines with very very high hours. This is why I have never heard about the ZDDP requirement.

[Barry Wolk]

I'm told that acids form because of the moisture content being the catalyst. Mine has little moisture content due to the engine block heater keeping condensation from forming inside the cold block. While not needed as a critical start, it's best for the engine to be warmed up and ready to instantly load up by being directly connected to the armature of the generator.

The unit runs for 45 minutes 52 time a year. That's only 39 hours a year of run time. How much acid could there be?

I did change the oil after running for 5 days straight in that massive northeast outage.

[Shelly Harris]

I too have an outside natural gas fueled Kohler generator like Barry's, but not as large. It too "exercises" once a week for about 15 minutes. Whether it needs it or not I change the oil filter and the 2 quarts of oil every October. I use synthetic which I was told unlike dyno oil will not gel up in winter temps. When I dump the oil always looks dirty. Changing oil is the cheapest, effective wayh to remove dirt from an engine. It's cheap. I don't understand why you wouldn't change it yearly.

[Barry Wolk]

It's not an automobile engine. Dirt is not much of a factor. Mine is an industrial Ford engine similar to a Pinto engine. After 5 years there was just a slight discoloration of the oil.

If your oil is black after a year of running it for only 13 hours a year there's probably something wrong with your engine. Everyone that's responded to this question on other sites, with lots of industrial engine experience, says that it's normal for the oil to stay clear for up to 10 years. The experts say that it's only the acids that build up that can be a problem, but that acids don't build up as rapidly with no moisture present.

Why waste oil if you don't need to?

[Don Henschel]

Combustion produces moisture and acid. The acid in turn accumulates in your oil. Next time you start up your car look at the water dripping from your tail pipe.:rolleyes: Like Shelly says the price of 2 quarts of oil and a filter once a year. As for gasoline being more corrosive I disagree with that. Do a google search for natural gas engines and acid monitoring for the oil. It appears to be a major concern. If you know any plumbers and gas fitters ask them about the required liners for Chimneys where natural gas is used. Our regulations up here are quite strict about that due to chimney failures from the corrosive nature of natural gas exhaust.

[Barry Wolk]

Then that's a perfect argument for longer oil changes on a standby generator. How much run time is it between oil changes for you?

If you change your car's oil every 3000 miles that's 50 hours at 60 miles per hour. Shelly's runs 13 hours total, all year long. After adjusting mine, it runs 26 hours, all year long.

If you're running synthetics in your car and you go 7500 miles between changes that's 125 hours of driving your car at 60 miles per hour. If you're using synthetic oil, Shelly, why would you go ten times as long between changes on your car than on your generator?

[Don Henschel]

If thats all it runs (I was too lazy to do the math:p) then acid should not be a problem;)

[Barry Wolk]

My C6500 bucket truck with the 454 gas engine has a system that determines oil changes for you. Since the engine runs the PTO for the boom it's in operation all the time we're using the arm, but the truck's not moving. You can't use mileage or time as the sole determining factors. I believe there's some type of pressure sensor on the oil pump filter circuit that has input into the equation.

All I know is that the truck has 100,000 miles on it but several hundred thousand hours on the motor, I'm sure.

[Don Henschel]

It's like alot of the haul trucks at the mine I work on. They have hour meters on them as well as odometers. We only pay attention to the hours. One of the last trucks I worked on had over 65000 hours showing on it and the hour meter wasnt working I was later told. Alot of hours on something that hauls up to 385 tons in one load!

[Shelly Harris]

Shelly, why would you go ten times as long between changes on your car than on your generator?
Why waste oil if you don't need to?

Barry ; By your criteria I'm sure I waste lots of oil. In addition to the generator I change oil and filters in two motorcyles evey October when I put them to bed for the winter. I use the cheapest 4 gals in each that I can buy from Wally World.... which is usually about $12 for each m/c. I start them up to get the oil circulating then shut them off till Springtime. Come Springtime I dump the never used oil and put in fresh good quality for the season----filter stays. On the Mark II and IV I'm changing oil every 500 miles and filter every other change. I'm intent on cleaning up whatever sludge they have. On a lexus 430SC and Jeep Cherokee, which are my "real" cars, it's strictly every 3K miles regardless of how long it takes to drive that distance (which is usually 6 months but could be lots longer). How's that for wasting oil?

[Barry Wolk]

I would agree. IMO, you waste a lot of oil.

I buy the best oil available and use it up.

Different strokes.

[Shelly Harris]

The only cheap oil I use is the winter m/c oil which I put in to protect from moisture and then dump in the spring. All other applications get good quality stuff. My goal is not extended use of oil, rather it's clean engine internals. I will agree my service is over kill. I will also admit to getting a good feeling dumping and changing oil this often, as it's surely not hurting anything and most probably doing good. Yea Blackhawks!!

[Barry Wolk]

I do change the oil in the Porsche every 1,000 miles per Porsche's original requirements. It really sucks getting that last half quart out of the filter canister with a turkey baster.

[Shawn Newcomb]

literally...:D

[Don Henschel]

If I don't drive it I don't change it period. I don't tend to exercise my Merc. or Mark very often and no I do not have problems with leaking seals at all. The pictures I posted of my frame showing the cross members missing, you will see a drop of oil hanging from my transmission output, well its still there threatening to drip on my floor. One member also commented on how clean the floor is under it. The only problem I had was my needle and seat stuck in my teapot due to varnish. I removed the top, gave the carb a quick flush out with spray carb cleaner and now it works fine. Constant short exercises not really allowing the engine to fully warm up probably create more harm in sludging than good (IMO).

[licorice]

The BEST way to see if you need to change oil is OIL SAMPLE, Also it is the cheepest part to change . My feelings is if you have to ask change it, it will not hurt. Been in repair buissnes since 1969. Large machines trucks and all .
Tony