Talking to my dad today, a pilot for over 60 years, and pretty mecanical. Has a '79 C-180. He has decided that he wants to go 40hrs. on filter changes, and 80hrs. on oil changes. He says the book recommends 100 hrs. on the oil changes. In an effort to save some money.

I have always changed my oil, and filters(Tempest-tall) at 35-45 hr. intervals.

Am I wasting money on oil, or better to keep doing what I have been doing? I would be happy to save money where I can, but not at the expense of my engine.

Most of my flying is at 5-8K', with occasional trips to 10K'. Power settings are generally 16-18"MP X 2400RPM

Thanks Gary

shortfielder wrote:In an effort to save some money.

Oil is the cheapest thing you stuff in a airplane. Why mistreat a $30,000 engine for 25 bucks worth of oil?

Up north when I was flying 1400 hours a year it wasn't an issue. The oil was barely in there when it would be time for a change. But down here at maybe 200 hours a year, I dump it at 25 hours. It's cheap.

Gump

Most people here are going with the 25 hour oil change and 50 on the filter. Gump is right oil is cheap.

25 hrs. is for when you have the screen instead of the filter, isn't it?? I'm puttin in 11 qts. at my changes.

Hey Gary, you know I'm on a tight budget like you might be. But, I've been told the same as what Gump said. In the grand scheme of things, oil and filter is cheap. Before I parked my plane and waiting for a new engine. I was changing my oil and filter about every 25 hours.

Yeah, I use a screen in the O-300. I use 7 qts Aeroshell multigrade and 1 pt Camguard every 25 hours, with screen cleaning. Most places I flew the big bore Continentals, we changed oil every 50, and filter every 100 hours. But in reality that worked out to about once every 10 days. And that was running engines hard. There was not much time for dirt/water to build up, and the oil always looked brand new as it came out..

On a less hours/"pampered" engine that didn't really get hot enough/flown enough, I would be changing oil a whole lot more frequently.

Gump

I fly 150-200/yr, so I am changing oil and filter every 3-4 mos.

if you are changing the oil why wouldn't you change the filter?? When you get your car or pickup oil changed I don't think anybody ever says please leave on the old filter?? Like everybody has already said oil is the cheapest thing you can put in your airplane I'm using Exxon elite and I think I'm liking it pretty well

I only have a screen in my O-300, so I have to change at 25 hrs.

For those who use multi-viscosity oils (20w-50, 15w-50, etc.) it's important not to run them for too many hours. Understanding how multi-viscosity oil works is important. The weight of the oil that they use to make it is the first number. Then, they put in a polymer additive whose molecules are a molecular chain with a special property. The molecular chain balls up into a little sphere when it's cold, and uncoils out straight when it's hot. When it's in the shape of a sphere, the polymer molecules don't interfere with each other, and the oil has the viscosity of 15 or 20 weight oil. When it's fully uncoiled, they interfere with each other, and the oil's viscosity increases to match 50 weight oil.

However, over time, the mechanical shearing forces inside of the engine chop up the molecular chains into smaller pieces. And, so you start out with 15w-50, some number of hours later it's down to 15w-45, or 15w-30, or whatever. I've never gotten a straight answer from an oil expert on the rate of degradation, the answer is always "it depends on the engine". I tried to analyze it once and found that my approximately 100 hour used oil (in my car) was definitely of less viscosity than new oil when they were both hot, but I didn't know how to measure the actual viscosity. I suppose that if it's a significant problem, it should show up on your oil pressure gauge.

Anyway, if you live in a really warm climate or always fully preheat your engine, you're probably better off with straight 50 weight oil.

tcraft
? is possably not changing the oil everytime, but changing the filter. And oil every other time.

The oil itself is a whole lot more important than the filter. There's lots of things to skimp on with airplane ownership. Oil is not one of them.

Gump

I dont look at oil changes as just a time to change the oil.. I use this as a chance to inspect the engine compartment for things falling off. We push our airplanes hard and it seems that anything over 33 hours the pilots squawk it before I find it on oil change. I would rather fix it on my time and not Sat morning with a bunch of people standing around.

Oil & Filter every 30 Hrs..I might go a little over 30 Hrs IF it has those hrs in a short period of time. Always get the engine warm before I drain the oil..so the crap goes out the drain easily. I never change oil on any of my equipment without changing filters.
Another thing..get the temperatures up when running any engine..the water condensation in a cold motor can really build up to a point where the oil will become milky..milky = bad lubrication.
HC

When I had an O-300 with a screen, I changed at 25 hours. When I went to a spin-on filter, I bumped that to 40 hours. Stayed wih 40-hour changes with the Lycoming, but am considering maybe dropping down to 30. I have about 26 hours on the oil right now & it seems pretty dark & kinda thin.

I wouldn't go over 50 hrs in the 182,, oil & filter. Used to aim for 25-30 with the Cont. on 560C (C-GOQY to me). On my Lyc with filter i go 50.

My son Joecub, made a good oberservation to me a while back, and that is that oil consumption always goes up a bit, starting at about 30 hours on engines with a filter, so we figured that 30 hours was a good time to change it, as the oil was probably getting a bit tired at that point. I agree that oil is not the place to get cheap, even tho I too am always looking for a way to save a buck. On my RV-4 with no filter, I change it every 25, cause that's what I've been doing with my planes for the last 45 years, and it works.
I've wondered about using Rotella or Delo, but never had the nerve to try it...

I have a Lycoming O-360 with a fllter in my scout. I change both the oil and the filter every 50 hours, which is just about every month. It has about 2600 hours on this engine, and I add 2-3 quarts between those 50 hours. I see no reason to change any sooner.

There's a lot of opinions on this topic - duh, just like everything else pilots opine upon! - but "old wives tales" is not the way to make up your mind. Start with the engine manufacturer's recommendations for hours between oil & filter change, then consider how the engine is used (how often it cruises, any special ops considerations, such as training aircraft that do lots of touch'n goes, dust, cold vs. hot conditions, etc.).

I believe most of the manufacturers (generally, all two of them ... Lycoming & Continental) generally recommend to change oil & filter every 50 hours, or every three months, whichever occurs first.

Do you benefit from changing the oil more often? I dunno ... actual data would be nice to base that decision upon. Yes, the cost of oil & filter is less than the cost of an engine rebuild, but over the course of an engine lifetime, it's certainly not insignificant. If one is changing the oil much more often than needed, the additional cost, at roughly $90-100 per oil & filter change (for an O-360 that takes 8 quarts per change, and assuming you do it yourself and your labor is "free"), can add up to a considerable waste. If the engine needs a change every 50 hours and you do it every 25 hours instead, over the course of a 2,000-hr TBO, the extra cost spent on 40 unnecessary oil changes is 40 x $100 = $4,000 ... which is about 25% of the cost of an overhaul on an O-360. It's not insignificant, despite what some have said on this topic. It'll be double the cost or more if you pay your local A&P to do it for you.

Yes, as one poster said, engine oil does break down with use, but keep in mind that the typical auto engine goes about 180-200 hours between oil changes per manufacturer's recommendations. So at 50 hours, per aircraft engine manufacturer recommendations, this is a small fraction of that oil lifetime. Yes, aircraft engines are built to much looser tolerances because they're aircooled and not liquid cooled, and the blow-by is much more than a typical modern auto engine deals with., so the oil gets dirty faster ... but still, the effect on the breakdown of long-chain hyrdrocarbons from engine heat and the shear forces on the oil are still roughly comparable to what any four-stroke internal combustion gasoline engine experiences - right?

Bottom line - it seems smart go with whatever the manufacturer recommendations are, as modified by the actual use your engine gets.

nmflyguy wrote:.......If one is changing the oil much more often than needed, the additional cost, at roughly $90-100 per oil & filter change (for an O-360 that takes 8 quarts per change, and assuming you do it yourself and your labor is "free"), can add up to a considerable waste.....

You might wanna do some comparison shopping-- I just ordered a case of Phillips XC2050 from the local bulk plant yesterday -- $49.14 dropped off at my house. And the last 6-pack of Tempest oil filters I bought from Spruce was $88, throw in some S&H & let's call it a c-note. That comes out to about $33 for 8 qts of oil & $17 for the filter for a total cost of $50 per change.

A couple of things to think about.

1.) The filter does not remove water or acid from the oil.

2.) They also do not remove particles smaller than 30 microns, which account for 98% of all wear.

25 hours, whether you use a sreen or filter, is the recommendation from the Chemist who developed Exxon "Elite" oil for Exxon , and among other things, Camguard.