Changing mind on oil changes

[hagrid]

Yes, 'splain plz.

 

[orangekuby]

Oil bypass is on delta pressure, not total pressure. If the oil is 100psi on both sides of the valve it's not going to open. It likely opens for a split second at start until the oil pressure equalizes on both sides, which will be very quick because it's already mostly full, it's just equalizing.

5w-40 oil is the same as 10/15w-40 when hot. It literally makes no difference if you have a winter and summer oil if both are a 40 weight. The 5/10/15w part is the thickness when cold, and 5w in summer at 100° isn't any worse than 15w because they will very quickly act like a 40 weight. 5w in winter, as noticed, will definitely be better than 10w/15w in frigid temps.

 

[SDT]

My M4500 doesn't get that many hours of use in a year, maybe 100-125. I've always done the change it once a year right before making first cutting hay in the spring thing.
Last year the factory sending unit for the oil pressure idiot light went bad and I was in a hurry to get things going so I just put on an oil pressure gauge I had laying on the shelf. Works fine and I can see the actual oil pressure.
Fast forward to winter.
Of course at 100 hours it's not due for a oil change on the 15-40 that I put in this spring but...
On that old oil the pressure REALLY spikes when cold, 20's or below. I mean as in 100 psi type of stuff anything much above 1/3 throttle until really, really warmed up.
You couldn't tell that with the idiot light because you just had to assume everything was good when the light went off at start up. So I've decided for a few extra bucks it gets a winter change with 5-40 diesel from now on.
This morning at 0 +/- it was 75 max after just a few minutes of warm up. I like that a lot better!!!
Does it hurt it to run that 100 hour oil through the winter and see those high pressures on a cool motor? Probably not, I mean this tractor is 40 years old and the motor has never been apart, but.....

Why not just use 10W30 diesel spec oil year round as recommended by Kubota?

 

[GreensvilleJay]

I wasn't trying to be 'smart' just wanting to know more about the tractor's history as the 1st post says it's 40 years old. I don't know anyone that is the 'one owner' of a 4 decade old vehicle(car,truck,plane or tractor ). None of the dozens of farm tractors I've bought came with 'log books' or 'records', so I have no idea when oil was changed, let alone grade. Just reading the 1st post ..40 year old, 100+ hrs per year puts 4000+ hours on the tractor so if it's never been apart someone's taken good care of it ! Later on, more info comes out.. you bought at 900 hrs, a few years ago. Say it was 10, then 900+(100x10) = 1900 hrs,less than 1/2 I was 'seeing' in your 1st post.

 

[DustyRusty]

You need to consider the oil's viscosity. 5W-40 will give better starting at cold temperatures but might be too thin at 100 degrees starting.

 

[TheOldHokie]

You need to consider the oil's viscosity. 5W-40 will give better starting at cold temperatures but might be too thin at 100 degrees starting.

Any grade of oil, even 0W16, will be way higher viscosity than needed at starting.

Dan

 

[GeoHorn]

Oil bypass is on delta pressure, not total pressure. If the oil is 100psi on both sides of the valve it's not going to open. It likely opens for a split second at start until the oil pressure equalizes on both sides, which will be very quick because it's already mostly full, it's just equalizing.

5w-40 oil is the same as 10/15w-40 when hot. It literally makes no difference if you have a winter and summer oil if both are a 40 weight. The 5/10/15w part is the thickness when cold, and 5w in summer at 100° isn't any worse than 15w because they will very quickly act like a 40 weight. 5w in winter, as noticed, will definitely be better than 10w/15w in frigid temps.

I agree that the by-pass valve is “delta”…. but if that congealed oil cannot pass thru the media without developing 8-psi-delta…. then the bypass will Open….and remain Open….until the oil warms up sufficiently to dissolve that congealed oil.

In cold wx such as we are presently experiencing…that may take a while.

(Makes a convincing argument for pre-heat.)

 

[PoTreeBoy]

Why not just use 10W30 diesel spec oil year round as recommended by Kubota?

For some reason, 10w30 has been hard to find around me so I started using 5w40.

 

[mcmxi]

Cooling and lubrication is dependent on flow and not pressure.

But pressure is generated when flow meets resistance, and pressure is indicative of flow. I like real oil pressure gauges and some of my vehicles have them. My '98 Jeep TJ for instance has a real oil pressure gauge and I can see the pressure vary as the rpm changes, which changes the flow rate of the engine oil.

 

[TheOldHokie]

But pressure is generated when flow meets resistance, and pressure is indicative of flow. I like real oil pressure gauges and some of my vehicles have them. My '98 Jeep TJ for instance has a real oil pressure gauge and I can see the pressure vary as the rpm changes, which changes the flow rate of the engine oil.

Its not quite that simple.

Fill your loader bucket with gravel and raise it to full height and leave it there. Whats the pressure in the base end of the cylinders and how much flow is going through them?

Or if you like raise it halfway when empty and then shovel it full. What was the pressure before and after filling and how much oil flowed?

Dan

 

[MountainMeadows]

"GeoHorn: How So?"

Overly high oil pressure can erode a rod or main bearing, from the lube hole area, where the oil enters the bearing, similar to the same way high water erodes away a stream bank. This doesn't apply to needle or ball type bearings.

 

[mcmxi]

Its not quite that simple.

Fill your loader bucket with gravel and raise it to full height and leave it there. Whats the pressure in the base end of the cylinders and how much flow is going through them?

That's like asking why the air in a compressor tank remains at some pressure even though the compressor isn't running. I simply stated that when flow of a fluid meets resistance, pressure is generated. Nothing more, nothing less. When work is done on a fluid, and the energy not transferred, then it has to be conserved, just like the air in a compressor or the hydraulic fluid in a closed system. The point is that the system is closed and able to conserve energy.

 

[TheOldHokie]

That's like asking why the air in a compressor tank remains at some pressure even though the compressor isn't running. I simply stated that when flow of a fluid meets resistance, pressure is generated. Nothing more, nothing less.

I know what you said and it confuses some people. They read more into it. I gave you the second scenario to differentiate it from your compressor analogy. I can provide a more interesting scenario if you like.

Just pointing out changes in pressure do not necessarily require a flow. Nothing more, nothing less.

Dan

 

[North Idaho Wolfman]

In 2021 Texas had a huge cold snap and the Electrcal grid was shut down due to near collapse. There was significant water damage to many homes

In 2022 Texas again had a cold snap and the Austin area had severe electrical outages due to negligence of trimming trees that were collapsing and causing power lines to fail. Some water lines freezing again.

Now in 2023 we are having a minor cold snap but everyone is still pretty gun shy about any cold weather situation and the grid control system (ERCOT) seems to like to issue alerts to keep everyone on edge.

UMMMM it's 2024.

 

[mcmxi]

Just pointing out changes in pressure do not necessarily require a flow. Nothing more, nothing less.

Pressure is defined as a force divided by an area. If pressure changes, then force or area or both have to change.

I know what you said and it confuses some people. They read more into it. I gave you the second scenario to differentiate it from your compressor analogy. I can provide a more interesting scenario if you like.

Just pointing out changes in pressure do not necessarily require a flow. Nothing more, nothing less.

Dan

This thread is about engine oil pressure and the related pressure gauge. It has nothing to do with the pressure inside hydraulic cylinders. Remind me again how an oil pressure gauge in an engine application is going to show any pressure once the engine is off? It's only going to show pressure when the engine is running and there's fluid flow.

Anyone who has had their blood pressure measured and seen it increase will understand that the increase is often related to a reduction in the cross sectional area of blood vessels.

 

[PoTreeBoy]

UMMMM it's 2024.

Frozen in time

 

[GreensvilleJay]

re: Remind me again how an oil pressure gauge in an engine application is going to show any pressure once the engine is off?

1) gauge is busted ,
2) needle sticks,
3) semi plugged passageway
and.....my favorite...

4) forklift's oil pressure gauge reads 30 PSI (running pressure) when key turned off. Turn key back on, gauge 'resets' to zero. This happened EVERY time over 14 years of owning the forklift.One mystery I never solved.

 

[TheOldHokie]

This thread is about engine oil pressure and the related pressure gauge. It has nothing to do with the pressure inside hydraulic cylinders. Remind me again how an oil pressure gauge in an engine application is going to show any pressure once the engine is off? It's only going to show pressure when the engine is running and there's fluid flow.

My comments are a bit more general. Depending on a number of things the engine pressure gauge could/will show pressure when the engine is running even if there is no flow. I am sure you know what I am getting at..

Pressure is defined as a force divided by an area. If pressure changes, then force or area or both have to change.

Now allow me to use a cylinder example to illustrate my point a bit further.

The piston in this diagram is 2" in diameter and the rod is 1" in diameter. This cylinder was pressurized on the base (red) end to raise the 2000 pound load while the rod (blue) end was open to atmosphere then both rod and base end were sealed. At this point the cylinder is completely filled with oil and the pressure gauge on the base end reads 636 PSI and the rod end gauge reads 0 PSI. That's using your arithmetic.

The double acting cylinder is allowed to sit for 24 hours and when we come back both gauges now read 2,546 PSI and the weight has not moved. What happened and how did I arrive at the new pressure?

 

[GeoHorn]

..

4) forklift's oil pressure gauge reads 30 PSI (running pressure) when key turned off. Turn key back on, gauge 'resets' to zero. This happened EVERY time over 14 years of owning the forklift.One mystery I never solved.

I believe that occurs to some electrically-powered gauges.

"GeoHorn: How So?"

Overly high oil pressure can erode a rod or main bearing, from the lube hole area, where the oil enters the bearing, similar to the same way high water erodes away a stream bank. This doesn't apply to needle or ball type bearings.

Mountains out of mole-hills and an illogical comparison between bearing types. I don’t care to spend any more time arguing that silliness.

 

[MountainMeadows]

I believe that occurs to some electrically-powered gauges.



Mountains out of mole-hills and an illogical comparison between bearing types. I don’t care to spend any more time arguing that silliness.

The Silliness is on you. I'm not comparing bearing types.