Extended Oil Changes - 100 Hours

Skymac

Skymac

Pre-takeoff checklist
Joined
Nov 9, 2015
Messages
326
Location
Kentucky
Display Name
Display name:
Justin
I figure I’ll be my own guinea pig, but just curious if anyone else has extended their oil change interval on high usage engines. I’m running a 0-320 around 100 hours every 5 weeks, so roughly 20 hours a week.

Sometimes I will catch oil changes at 45 hours, and others at 60 hours just depending on timing. With today’s slightly more modern oil, and spin on filters I’ve been tempted to go a full 100 hours before change and oil analysis. The way I see it is I’m adding 1 quart around every 12 to 14 hours, so that’s around 8 quarts per hundred hours, not to mention the oil doesn’t have much calendar time on it.

I use Aeroshell 15w-50

More of a curiosity than anything to compared Blackstone samples between a 50 and 100 hour interval but with the problem of getting filters and oil, it’s peaked my curiosity. I wouldn’t normally do this on a airplane that’s not running at a high utilization.

Flame suit on!
 
Last edited:
Skymac said:
I figure I’ll be my own guinea pig, but just curious if anyone else has extended their oil change interval on high usage engines. I’m running a 0-320 around 100 hours every 5 weeks, so roughly 20 hours a week.

Sometimes I will catch oil changes at 45 hours, and others at 60 hours just depending on timing. With today’s slightly more modern oil, and spin on filters I’ve been tempted to go a full 100 hours before change and oil analysis. The way I see it is I’m adding 1 quart around every 12 to 14 hours, so that’s around 8 quarts per hundred hours, not to mention the oil doesn’t have much calendar time on it.

I use Aeroshell 15w-50

More of a curiosity than anything to compared Blackstone samples between a 50 and 100 hour interval but with the problem of getting filters and oil, it’s peaked my curiosity. I wouldn’t normally do this on a airplane than running at a high utilization.

Flame suit on!
Click to expand...

No flame suit needed from me as long as it's your plane and not mine. I learned long ago that the two of the cheapest things I would spend money on for my plane was fuel and oil changes.

I suppose that there is some merit to the fact that oil technology has been greatly improved over the last few years. Interested to see what others think of your hairbrained innovative idea. ;)
 
Does this o-320 happen to run on mogas? Seems like lead contamination is going to be the biggest obstacle. Might be worth a call to Blackstone to see if they have anyone doing it.

Seems like there a noticeable decrease in viscosity at 50 hours, so it may be that the heat and shear actually wear it out in that time.
 
BTW it's "pique".

"Piqued my curiosity"

Just a pet peeve of mine. Piqued my ire.

Their/ they're/ there
Brake/break
Etc.
Carry on.
 
Skymac said:
I figure I’ll be my own guinea pig, but just curious if anyone else has extended their oil change interval on high usage engines. I’m running a 0-320 around 100 hours every 5 weeks, so roughly 20 hours a week.

Sometimes I will catch oil changes at 45 hours, and others at 60 hours just depending on timing. With today’s slightly more modern oil, and spin on filters I’ve been tempted to go a full 100 hours before change and oil analysis. The way I see it is I’m adding 1 quart around every 12 to 14 hours, so that’s around 8 quarts per hundred hours, not to mention the oil doesn’t have much calendar time on it.

I use Aeroshell 15w-50

More of a curiosity than anything to compared Blackstone samples between a 50 and 100 hour interval but with the problem of getting filters and oil, it’s peaked my curiosity. I wouldn’t normally do this on a airplane than running at a high utilization.

Flame suit on!
Click to expand...

Sounds like a great way to induce blue flu.
 
Ahh the grammar police! Haha scary…

I’ll make sure to come to come back in a month or so with a Blackstone report. Obviously lead should be increased, but it will be interesting to see the other numbers. The engine is well beyond TBO and has a replacement shipping this week. If lead is the only value really elevated - At what point would we consider lead at a dangerous level.

I’m all for running a lead free alternative, although I hope the smell is not like auto fuel!
 
There ARE tests to determine if the oil is acceptable for continued use.

Some of the Oil Analysis folks have provided this service. Not sure if they still do.
 
Skymac said:
I figure I’ll be my own guinea pig, but just curious if anyone else has extended their oil change interval on high usage engines. I’m running a 0-320 around 100 hours every 5 weeks, so roughly 20 hours a week.

Sometimes I will catch oil changes at 45 hours, and others at 60 hours just depending on timing. With today’s slightly more modern oil, and spin on filters I’ve been tempted to go a full 100 hours before change and oil analysis. The way I see it is I’m adding 1 quart around every 12 to 14 hours, so that’s around 8 quarts per hundred hours, not to mention the oil doesn’t have much calendar time on it.

I use Aeroshell 15w-50

More of a curiosity than anything to compared Blackstone samples between a 50 and 100 hour interval but with the problem of getting filters and oil, it’s peaked my curiosity. I wouldn’t normally do this on a airplane that’s not running at a high utilization.

Flame suit on!
Click to expand...
I have 3 more filters then I am switching to the Challenger oil filter.
I run my oil to 55 hrs in my 0-320 motor and change the filter also.
I fly about 250 hrs a year.
Couple years ago I ran the oil to 100 hrs in a 0-320 that I was going to change out. I sent a sample to Blackstone. They said it was fine all metals were within averages. No problems were noted.
I think for as much as your flying it that 100 hours oil changes are fine.

I have been changing oil for my own fleet of trucks since 1983 and have always extended the drain interval.
IMG_1551.JPG

I had taken all 4 clys off the motor and inspected the cam. Then I put it back together and ran it 98 more hours. It would have run another 1000 hrs but unfortunately I ordered another motor. The high silicon numbers were from new silicon valve cover gaskets not from the air filtration. IMO I saw the same thing on a new lycoming engine, the silicon went down after each oil change to below averages.
IMG_8282.JPG
 
Last edited:
Here are the reports for the new motor, silicon readings went down as time went by. It had silicon valve cover gaskets from lycoming when new. I am running a challenger air filter that I keep clean.
(edited)_IMG_1080.JPG
 
Thanks for the reply. I have a higher copper reading as well on my O-320, with with clean filters and screens it doesn’t seem to be an issues. It’s been elevated since it was new and has 1200 hours or so on it now. I miss typed earlier, my engine over TBO is the O-360.
 
Depending how many quarts is being added/put in over those 100 hours, you may not need to change the oil! :D
 
I have no scientific data to support either case. I try to get close to the 50 hour mark and I will say even with adding quarts every 10 hours or so it's pretty nasty looking when I drain it. I can also tell you at 50 hours 8 quarts of oil drains out in about the same amount of time it takes to pour 1 quart of fresh 100W.
 
Grum.Man said:
I have no scientific data to support either case. I try to get close to the 50 hour mark and I will say even with adding quarts every 10 hours or so it's pretty nasty looking when I drain it. I can also tell you at 50 hours 8 quarts of oil drains out in about the same amount of time it takes to pour 1 quart of fresh 100W.
Click to expand...

Honestly the appearance of the oil doesn't mean much. I have got labs on oil that looked clean that would make me hesitant to run the oil in a weedeater. I have also gotten results that were great on oil that looked black like asphalt.
 
zodiacflyguy said:
Honestly the appearance of the oil doesn't mean much. I have got labs on oil that looked clean that would make me hesitant to run the oil in a weedeater. I have also gotten results that were great on oil that looked black like asphalt.
Click to expand...
\
I agree, as soon as I put fresh oil in a diesel engine it turns black, yet the engines have run for 500,000 miles in the city.
 
Some oils change color with heat that can give the impression of dirty oil.

Put a kidney in your engine? Bypass type filters take a small amount of oil and pass it through a dense filter media. This enables removal of particles far smaller than what a full - flow can capture. Most large trucks use this ( Lube Refiner):and car guys will not accept them. Note: in addition too. Not instead of.

“Guaranteed to keep your oil analytically clean” was the advertising. The unit was the AeroFrantz Oil Filter. It was STC’d but marketing was terrible. Bell 47 guys seemed to like them as engine oil also flowed through transmission IIRC. FRAM also produced aircraft bypass filters.

One test of evaluating oil involves 4 steel balls. One ball is rotating and pressed into the other 3 under increasing pressure and temperature while in an oil spray.
Ultimately the balls will seize. When is dependent on how effective the “lubricity?” Is.
 
I was influenced by a late uncle that I worked for in the late 70s. He had 2 company vans that he drove all over the country. He used amsoil and special filters. I forget the details but he got 100s of thousands of miles out those dodge vans.
He surely didn’t change oil every 3000 miles. I helped him maintain those vans when I was young and it helped me as I grew older.
 
How many of you have seen the toilet paper roll sidestream oil filter? My grandfather installed them on the small fleet of pickups that were used in the family owned commercial sheet metal contracting business he and my Dad owned.

I had to change the oil in the trucks beginning when I was about seven. It made a freekin' huge mess prying the TP roll out of the filter can and forcing the new one into place.
 
Those toilet paper filters were based on the paper that was sold in the '50s and '60s. It was real paper and worked great. My uncle used one on his Studebaker.

Modern toilet paper is "Eco Friendly," and will dissolve in minutes.
 
See #22

IKO4 nailed it.

Aircraft elements had the “ FAA Approved” stamp on them. They DID cost more.

Pushing dirty oil through 4 in of element will really clean it up.

As a distributor; we had a Demo Machine. This was a clear plastic “ crankcase” and you could select between the Frantz and the full flow of your choice. Lampblack and water were added to the “crankcase”. The full flow removed none of the contaminates and rye Frantz removed almost all. It would hold about 1/2 cup of water.

It’s really an unfair test. The full flow could handle maybe 40 qts/min flow so it could not have restrictions. The Frantz bypass would only allow 2 qts/min through the 1/16 inch orifice.

Solution ? Have both.

No one has ever asked me to remove the unit or refund $$.
 
As promised, here are the latest numbers I’ve had a few oil changes since the November oil change in 2021. I actually forgot that I had ran that one a few extra hours longer as well, but I think it shows a good comparison.

The engine produces a clean oil sump screen and the filter media also showed no concern.


cafee873106692fd8e0eee848dac8cd2.jpg
 
Wear metals are not the be-all and end-all of engine or oil condition. I used to do my oil regularly, as I had access to atomic absorption, ICP-optical emission, and Total Reflection X-Ray spectrometers at work. (We often ran teaching labs on my airplane oil samples.) The wear metal analysis was generally not very informative about engine condition, TBH, and about the only thing it ever caught that I was not made aware of independently was a leaky air filter (high silicon). High usage oil is going to build up carboxylates through high temperature dependent breakdown and oxidation, which will render the oil increasingly acidic over time. Changing that out periodically will reduce internal corrosion risk. In 35+ years of ownership, I practice the mantra that "oil is cheap, metal is expensive."
 
chemgeek said:
In 35+ years of ownership, I practice the mantra that "oil is cheap, metal is expensive."
Click to expand...

I do oil analysis but it's only one of many tools to use in determining engine health. A friend caught a failing cam gear in his experimental aircraft engine by using oil analysis.

I like to keep an eye on oil pressure ... especially the hot idle oil pressure after a flight.

I agree that oil is cheap (relatively) and it's easy enough to install. :)
 
I agree…. In this case though it’s just for comparison. Oil is cheap true, but I’m going to quit being so wasteful at least until the temps get into the 90’s then I’ll probably go back to 50 range just because. Filters have been tough to come by. Anywho, do as you wish :)
 
EdFred said:
Depending how many quarts is being added/put in over those 100 hours, you may not need to change the oil! :D
Click to expand...

You are changing the oil to remove contamination not because the oil is failing. It doesn’t matter how many qts you have added.
50 hours is also a good interval for inspecting the engine with the cowl off.
 
Jeff767 said:
You are changing the oil to remove contamination not because the oil is failing.
Click to expand...
The viscosity modifiers in multigrades degrade, which is why they appear thinner when they're drained, if they're at room temperature like the new oil.

https://www.sae.org/publications/technical-papers/content/982638/

https://www.savantlab.com/testing-highlights/testing-shear-stability-and-viscosity-loss/

Since a multigrade is a low-viscosity oil that has those modifiers added to it, the loss of the modifiers over operating hours takes the oil back toward it's low viscosity. 15W50 going back toward SAE 15 (Aviation 30) oil when it's hot is not a good deal at all. It can't lubricate well, and highly loaded interfaces such as between the cam and lifter can suffer. Not much economy there.
 
The turbines I work on never get an oil change. Good old PT6's!
 
In recent years the oil folks have added a date similar to “ best if used by” to
the containers. Additives separate with time even outside the engine.
 
Magman said:
See #22

IKO4 nailed it.

Aircraft elements had the “ FAA Approved” stamp on them. They DID cost more.

Pushing dirty oil through 4 in of element will really clean it up.

As a distributor; we had a Demo Machine. This was a clear plastic “ crankcase” and you could select between the Frantz and the full flow of your choice. Lampblack and water were added to the “crankcase”. The full flow removed none of the contaminates and rye Frantz removed almost all. It would hold about 1/2 cup of water.

It’s really an unfair test. The full flow could handle maybe 40 qts/min flow so it could not have restrictions. The Frantz bypass would only allow 2 qts/min through the 1/16 inch orifice.

Solution ? Have both.

No one has ever asked me to remove the unit or refund $$.
Click to expand...
I had a Frantz filter on a Chev S-10 many years ago. It did keep the oil pretty clean, by stopping the smaller particulates that color the oil. But that's all it did; it could not correct acidic or alkalinic oil. It couldn't restore viscosity modifiers.

I still have that Frantz. I recently drilled out the small orifice, made a couple of adapter sleeves to fit the "modern" toilet paper rolls that have a larger core so as to cheat you out of some paper, and I run my compressed air through it to trap moisture and oil mist when I am painting. Seems to work OK. The pressure regulator is upstream of the filter to avoid overpressuring the canister.
 
Did you do oil analysis?

To clarify; I’m not concerned with contaminates but rather the condition of the oil.
While my presumption is not too many people do Oil Analysis on private vehicles I would welcome comments from an independent source. My involvement ended over 40 years ago.

I’m guessing heavy truckers and construction equipment may do so; since many of them use bypass filters and have extended oil changes.
 
Last edited:
Magman said:
Did you do oil analysis?


I’m guessing heavy truckers and construction equipment may do so; since many of them use bypass filters and have extended oil changes.
Click to expand...


To the tune of 20k miles or better. I have an AmsOil on my truck.
 
Unit74 said:
To the tune of 20k miles or better. I have an AmsOil on my truck.
Click to expand...
I have newer Detroit diesel that get's oil and filter changes every 35K miles. All filters are cartridges and are above the frame rails. No getting under truck to change filters.
 
Skymac, it's interesting that the viscosity did not diminish much, with 88 hours on the oil. It's still in the middle of the range where it's supposed to be.

It's also interesting that your lead accumulated to only 5k ppm. That's about the same as for my IO550 engine after just 43 hours.

I'm guessing that O320's smaller engine size, along with replenishing eight quarts, might explain most of that. But just the same, it's impressive that viscosity and lead, the two things I would worry about for an extended oil change, were just fine after 88 hours.
 
NoHeat said:
Skymac, it's interesting that the viscosity did not diminish much, with 88 hours on the oil. It's still in the middle of the range where it's supposed to be.

It's also interesting that your lead accumulated to only 5k ppm. That's about the same as for my IO550 engine after just 43 hours.

I'm guessing that O320's smaller engine size, along with replenishing eight quarts, might explain most of that. But just the same, it's impressive that viscosity and lead, the two things I would worry about for an extended oil change, were just fine after 88 hours.
Click to expand...

I thought exactly the same.

It’s not something I’m going to worry about in the future. Still routinely change the oil at 50, but when I can’t seem to get to it, I’m not sweating over it from here on out.
 
You must log in or register to reply here.
Back
Top