Oil filter change interval

Domenick

Domenick

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Domenick
For 20+ years I've been changing my oil filter at every 50 hour oil change, cutting it open, and finding nothing. Oil samples sent to Blackstone. This spans two Lycoming O-320-D3G engines.

Some pilots run an oil filter for two cycles, in my case this would be 100 hours. Comments on two cycles versus one cycle?
 
I do the exact same as you have been doing for the last 10 years. Every 50 hours, always some glitter and Blackstone always telling me to watch this metal or that metal never had a hiccup but always nervous as hell opening that filter or awaiting that report.
 
A lot can happen in 100 hours. To me the cost is well worth it to see that the engine isn't making metal. I'd be willing to bet that an engine making metal will make it to the next 50 hour without a catastrophic failure, but 100? I'm not so sure.
 
Easy to drain through a paint strainer to check for metal.

Not too many do though.

Some folks are such perfectionists that the paint on the safety wire on the

Suction Screen is an exact match to the engine.

At 15 SMOH!
 
Domenick said:
Some pilots run an oil filter for two cycles, in my case this would be 100 hours. Comments on two cycles versus one cycle?
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If one decided to run the filter 2 change cycles, might still send a sample to Blackstone, just for piece of mind. The filter savings would basically pay for the analysis.
Editing to add:
I'm not advocating for or against keeping the filter for an extra cycle, just that the oil analysis is an option to somewhat check things out if you choose to.
I can't remember a time in the many many oil changes I've done over the years, on cars, trucks, motorcycles, etc., that I didn't change the filter. Just don't feel right. Much less on something that I'm flying.
I am also always a bit surprised how nice and caramel-ly the oil looks on the stick, but how black as hell it looks in the recycle jug.
Makes me think that filter has to have at least some restriction. If the filter media is doing anything at all.
 
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I normally do the same, new filter with change. I wouldn’t have a problem with a little variance, filter in for another cycle. It just seems best to start clean.

Besides any hour interval, we have calendar time, should be factored in.

I’m kinda awash in oil now. I’m a sucker for that ride later in the day at Oshkosh.
 
Domenick said:
For 20+ years I've been changing my oil filter at every 50 hour oil change, cutting it open, and finding nothing. Oil samples sent to Blackstone. This spans two Lycoming O-320-D3G engines.

Some pilots run an oil filter for two cycles, in my case this would be 100 hours. Comments on two cycles versus one cycle?
Click to expand...

I use the same maintenance schedule on my Lycoming IO-320 as you and cut the filter open and spread out the element looking for metal.

The cost of the filters is annoying but I feel well worth it.

How dark the oil is has a lot to do with the sort of flying I have been doing.

I am currently at 2,254 hours and the engine has good compression and is not making metal that I can see.
 
Skyrys62 said:
If one decided to run the filter 2 change cycles, might still send a sample to Blackstone, just for piece of mind. The filter savings would basically pay for the analysis.
Click to expand...

Is it about $30-40 for an oil analysis?
 
mandm said:
Is it about $30-40 for an oil analysis?
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$25. Less if you buy a package of 10 at Oshkosh. Other places are cheaper than Blackstone, but I really like their commentary, and they do a lot of aircraft, so they know what they're looking at. The owner/founder is an aircraft owner.

Edit: looks like they've gone up since I bought mine. Your 30-40 number is right on.
 
Some of the cheapest parts you'll ever buy for your plane are filters and oil, and are pretty easy to install ...
 
What you are doing is changing most of the oil, but not all when you don't change the filter, which holds about a quart, Why? You could always unscrew the filter and dump the oil, then reinstall the old dirty filter, Penny wise dollar foolish.
 
The first I had heard about 100hr cycles was a result of the prior recent oil filter shortage. Never heard of that before then.
 
I change the oil about every 25 hours. Phillips 20w-50 and cam-guard. My engine does not burn much oil. The oil filter gets changed every other oil change. So, every 50 hrs. As recommended. Oil is easy to change. Oil is cheap, especially in a 3 way partnership. I always have two cases on hand. Send out to Blackstone for analysis.
 
Morgan3820 said:
I change the oil about every 25 hours. Phillips 20w-50 and cam-guard.
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Same here.
Morgan3820 said:
The oil filter gets changed every other oil change. So, every 50 hrs. As recommended.
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That doesn’t seem like a bad idea on paper. Since the filter is getting changed at the regular interval (50hrs) would there be any issues running the filter for 50 and just changing the oil in the pan every 25? @Bell206 @Dan Thomas
 
Luigi said:
What you are doing is changing most of the oil, but not all when you don't change the filter, which holds about a quart, Why?
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I'm curious what the total oil retention is both with/without replacing the filter. Of course the filter retains a lot, but so would other parts of the engine (+propeller/governor on a CS). Anybody have numbers for these different retention scenarios?

Making up numbers here, but if engine+prop retains, say, 2qt, and oil filter retains another 0.5qt, it feels like less of a meaningful difference.
 
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The amount of oil in the oil passages is very small. It’s not going to make a difference in engine longevity.
 
"You think oil changes are expensive? You could always skip some and then learn what 'expensive' really means" -A&P at my first oil change

My math...
Oil filter: 35$ ish?
Oil interval: 50 hours

About 0.70$ per hour of operating cost goes towards the filter. So unless there is some soviet union-esque style shortage of oil filters that will prevent me from flying, it's getting changed at least every 50 hours.
My peace of mind is worth more than a few quarters per hour :).
 
It’s well established that burning a gallon of fuel creates a gallon of water ; or similar.

Ground running or numerous short flights can allow water to build up in the oil.

Another run spreads the water around and results in rust.

One way to remove water is longer flights.

Many Radial Engines have sump drains in their tanks to check periodically.

We could consider doing similar via quick drains that may be easy on some aircraft.

Maybe drain a cup once in a while?

Is water content reported in oil analyses?
 
Morgan3820 said:
I change the oil about every 25 hours. Phillips 20w-50 and cam-guard. My engine does not burn much oil. The oil filter gets changed every other oil change. So, every 50 hrs. As recommended.
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This is basically what I end up doing, but the only reason is because of time on the oil. I don't fly much, so I try to get fresh oil in the engine every 3-4 months. I'm not going to change the filter every 20-25 hours.
 
When using “ Clean Catch” it’s possible water may have settled and been dumped depending on time.

No idea how long it takes to separate.

Maybe I’ll check a few, cold.
 
FYI. Full flow oil filters remove very little water from the oil..

Bypass type is needed to do thst.

Ideal is to have BOTH as per the majority of heavy trucks.
 
A full flow will absorb only a very small amount of water as the media is rather thin. ( .020 ?) whereas the bypass type has almost completely filled with absorbent media and may hold about a 1/2 cup of water in suspension.

Cut them open to see for yourself.
 
Magman said:
A full flow will absorb only a very small amount of water as the media is rather thin. ( .020 ?) whereas the bypass type has almost completely filled with absorbent media and may hold about a 1/2 cup of water in suspension.

Cut them open to see for yourself.
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Interesting. Does that actually make a difference in the water content of the oil? How many hours worth of engine operation water in the crankcase does that equate to?
 
Most engines I encounter do not wear out but rather rust out.

This affects the Cam and Cylinders a lot.

Removing water from the oil/ engine should result in less rust.

Two strategies of doing this are a bypass filter and an Engine Dryer.

The latter uses an aquarium pump to force air through desiccant filled jars

and into the Crankcase . I’m convinced dry air in the engine is a good thing,



Really hard to determine a number of hours on this. Ground running, short flights,

low oil temps are not conducive to boiling off the water that continues to be

generated. No simple answer here. Engines that fly often last longer.
 
Magman said:
Most engines I encounter do not wear out but rather rust out.

This affects the Cam and Cylinders a lot.

Removing water from the oil/ engine should result in less rust.

Two strategies of doing this are a bypass filter and an Engine Dryer.

The latter uses an aquarium pump to force air through desiccant filled jars

and into the Crankcase . I’m convinced dry air in the engine is a good thing,



Really hard to determine a number of hours on this. Ground running, short flights,

low oil temps are not conducive to boiling off the water that continues to be

generated. No simple answer here. Engines that fly often last longer.
Click to expand...

Gotcha. So would a bypass filter mostly only help for short operation? During a long flight the crankcase should reach equilibrium moisture content either way.

I suppose that during low-power ops at the end of the flight the bypass filter could absorb extra moisture so when you power off the oil moisture content is lower, is that the idea?
 
Frequent longer flights ( 1 hr+) should reduce the need for a bypass filter as far as water.

Oil flow through a bypass filter is relatively constant as long as oil pressure is constant.

There is a .060 orifice at the “ downriver” side of the unit.

I’m not sure if water accumulates at varying rates.
 
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