Onan Oil?

[pasdad1]

Originally Posted by Ray,IN

To my thinking, if you have a 190*F thermostat in your engine, synthetic oil will not change that operating temperature. And then, there is this old thread that involved a lot or research: Synthetic lubricants-aren't.

The oil usually runs at hotter temperatures than the water. So it's possible that the synthetic - creating less friction - runs cooler.

[barmcd]

Originally Posted by pasdad1

The oil usually runs at hotter temperatures than the water. So it's possible that the synthetic - creating less friction - runs cooler.

Friction isn't what heats up an internal combustion engine--its the thousands of explosions in the cylinders every minute. The water jacket removes the heat from the engine and dissipates it thorough a heat exchanger--a radiator. If it has a 190 degree thermostat, then the engine is going to heat up to 190 degrees and stay there regardless of what type of oil you are running.

[pasdad1]

Originally Posted by barmcd

Friction isn't what heats up an internal combustion engine--its the thousands of explosions in the cylinders every minute. The water jacket removes the heat from the engine and dissipates it thorough a heat exchanger--a radiator. If it has a 190 degree thermostat, then the engine is going to heat up to 190 degrees and stay there regardless of what type of oil you are running.

If you could measure the oil temperature, you would see that it doesn't match the water temperature at all times.

[TQ60]

Oil is the friction bearing in the main and connecting rod as well as rinsing the cylinder walls.

The oil can get very hot thus the oil coolers on most new hd engines.

[Old Scout]

Probably stupid but I try to stay with manufacturer recommendations on oil and filters. Early in the equipment life-cycle, I figured it would make any warrantee discussions easier. After warrantee expiration, it probably doesn't matter so much. Been pleasantly surprised by prices at Cummins here In San Antonio. They sell Valvoline and OnanMax at competitive prices, and filters too. Often thought about trying to buy "cheaper" but for a once a year oil change, not a big deal. Have used Valvoline in Onan genset but price is about the same per qrt at my Cummins. Prefer not to have to carry different type of oil and coolant on the road so gallon of 15w-40 and one of ES Complete is all I need. Have heard there are issues as to how some filters are built and valved--might be a non-issue but why chance it?????

[spritz]

1982 Genset 6.5, Gas
Straight 30 weight oil and a Fram Filter.

Is it still true once you change over to Synthetic you can't go back to reg oil?
Tim

[BrianGlenn]

Very little difference in heat capacity (ability for oil to remove heat) for new mineral oil and synthetic oil. Mineral oil with additives (pretty well all oils sold retail) and synthetic degrade similarly. Mineral oil without additives will degrade more rapidly and loose heat capacity. I was aware of this study. http://docsdrive.com/pdfs/medwelljou...06/495-499.pdf

As mentioned the cooling system is the primary system for controlling temperature inmost of our engines. Some generators may be air cooled without glycol cooling. I do not know what oil temperatures they run at as I have never seen a oil temperature sensor on units like these. If the manufacturer does not prohibit the use of synthetic oil I would probably run synthetic as it does not degrade as quickly with higher temperatures. I run it in gas turbo engines that have oil cooled turbos at 1500F.

My thought,
Brian
Chemical Engineer (retired, but worked in lubrication blending plant)

PS. I swap between synthetic and mineral oil in my engines depending on what is on sale.

[twinboat]

Originally Posted by barmcd

Friction isn't what heats up an internal combustion engine--its the thousands of explosions in the cylinders every minute. The water jacket removes the heat from the engine and dissipates it thorough a heat exchanger--a radiator. If it has a 190 degree thermostat, then the engine is going to heat up to 190 degrees and stay there regardless of what type of oil you are running.

Oil plays an important part in engine cooling.

Many diesel engines have piston coolers in them. They are nozzles that shoot oil up into the hollow of the pistons, where the wrist pin is.

The oil absorbs the heat, falls to the pan and back thru the oil cooler, which is in the coolant loop.

[dix39]

To add a little to twinboat's post, my 5.9 Cummins had a liquid to liquid oil cooler where engine coolant was used to cool the oil

I used Rotella 5W40 synthetic in the old Onan which seemed to like it all right, and therefore in the newer one also. I also use this in all my motorbikes. IMHO, it covers about all the bases, 5W for very cold when the oil would normally be thick and slow to circulate, and 40 for warmer temps.

I previously used Rotella 15W40 in the Honda trail 90s. One one year I was elk hunting with one of the 90s at near or freezing temps. I couldn't crank it fast enough to get it started because of the thicker oil. Since then I've used 5W40 in all the bikes and the Onans.

Just my 2c.

Steve

[Luv2go]

Originally Posted by dix39

To add a little to twinboat's post, my 5.9 Cummins had a liquid to liquid oil cooler where engine coolant was used to cool the oil ....
Steve

Our 6.8L V10 gas engine has a liquid to liquid oil cooler as well. It's right where the oil filter is.

[barmcd]

Originally Posted by twinboat

Oil plays an important part in engine cooling.

Many diesel engines have piston coolers in them. They are nozzles that shoot oil up into the hollow of the pistons, where the wrist pin is.

The oil absorbs the heat, falls to the pan and back thru the oil cooler, which is in the coolant loop.

I never said oil is not important, but no liquid cooled engine is going to run cooler because it has synthetic oil in it no matter how much it reduces friction. If the engine generates less heat, the thermostat will just remain closed longer and the temperature the engine operates at will be the same. No liquid cooled engine will operate below the thermostat operating temperature for more than a few minutes. I was addressing a comment that an engine with synthetic oil in it would run cooler.

[pasdad1]

Originally Posted by barmcd

I never said oil is not important, but no liquid cooled engine is going to run cooler because it has synthetic oil in it no matter how much it reduces friction. If the engine generates less heat, the thermostat will just remain closed longer and the temperature the engine operates at will be the same. No liquid cooled engine will operate below the thermostat operating temperature for more than a few minutes. I was addressing a comment that an engine with synthetic oil in it would run cooler.

Many times liquid cooled engines operate much hotter than the opening point of the thermostat because of extreme engine load, ambient air temperature, efficiency of the radiator, etc. If a synthetic oil can reduce friction and heat generated, then the cooling system will have less heat to dissipate, and the engine will run cooler (closer to the opening point of the thermostat).

[ahicks]

Another Rotella fan as well.

Bottom line though, in my mind, is to run whatever you're comfortable with. If it's working well in your car/truck, the Onan will be fine on it. The more important thing, is that it be serviced regularly. Do that, and it will live a long happy life.

[vsheetz]

I used oman filters and oil in the 5500 in my previous coach. That said, I agree that any that is appropriate is ok. More important is that it's done regularly.