Question Oil change - flight time vs calendar time?

[Neal]

Sadly I have not flown much the last 6 months, in duration at least. Been doing shorter flights probably from dealing with my tail wheel shimmy which I finally resolved. My last oil change was July and that is SIX (ugh) TACH hours ago. I typically change my oil at around 25 TACH hours. The oil still looks new, no darkening or discoloration, obviously. Lycoming recommends 4 months as max duration (calendar).

What are the opinions on oil changes in scenarios like this where it's a calendar vs. engine runtime issue?

Yeah yeah, the saying is the cheapest thing you can put into the plane is oil....

 

[Cactus Charlie]

I sold my PA-28-180 with over 3,000 hours since overhaul. Oil was changed at 50 hours or 12 months. Once I had the FX-3 12 months came first.

My FX-3 is changed at 50 hours or 6 months.

I live in Arizona where condensation build up is a non-issue. I pulled cylinder 3 of that PA-28 at 2,800 hours. The 3 visible cam lobes and followers were bright, shinny, and perfect.

Note that Lycoming qualifies the 4 month interval with this note -

"** Oil change intervals must not exceed 4 months if the aircraft has not been flown for at least 25 hours in a 4-month period. More frequent oil changes are recommended if the engine has been exposed to volcanic ash, particulate, sand, dust debris, extreme weather conditions, or salt spray in coastal environments."

 

[Neal]

Guess it's time to change the oil. What a waste

 

[ve6yeq]

I just added another qt of W100 and 1.6 oz of Camguard before the last flight, as the level was getting low, and I am using about a qt every 15 hours at present. With only 5 hours left before the change (which will be 35 hrs and almost 3 months - the limit that Camguard recommends), I too have the same feeling of am I wasting "good" oil?

 

[Neal]

I just added another qt of W100 and 1.6 oz of Camguard before the last flight, as the level was getting low, and I am using about a qt every 15 hours at present. With only 5 hours left before the change (which will be 35 hrs and almost 3 months - the limit that Camguard recommends), I too have the same feeling of am I wasting "good" oil?

If you're getting close I wouldn't add oil. It can actually get far lower than we would ever allow.

I assume you're "not" using AeroShell as you're adding camguard?

 

[ve6yeq]

I assume you're "not" using AeroShell as you're adding CamGuard?

I use Aeroshell W100 and 5% CamGuard Aviation, as I think the additives in Aeroshell W100 Plus are nowhere near as good as those in CamGuard, based on what I have read.

If you're getting close, I wouldn't add oil. It can actually get far lower than we would ever allow.

I know the Cubcrafters AMM says 6-7 qt recommended, with a min of 4 qt, but in my limited experience, if I add more than 6 qt W100 + 10 oz CamGuard during an oil change, it just ends up out the oil sump breather tube. So, on the dipstick, I am operating between about 6 and 5 as measured on the ground with 29" tires, as I have never tried raising the tail to see what effect the deck angle has on the oil dipstick. The dipstick is at the back of the engine, and thus it would appear that it should read higher if the deck angle is higher.

 

[Cactus Charlie]

I know the Cubcrafters AMM says 6-7 qt recommended, with a min of 4 qt

I add 6 at oil change. That puts the level at 5.5 after engine run. I usually don't add any until it drops to about 4.5, sometimes as low as 4 qt, then add 1 qt.

I've been operating Lycoming parallel valve 360 engines for over 25 years. I never had a problem with high oil temperature even in AZ summer heat. My tired old O-360 would blow oil out the breather if run higher than about 6 qt. Never blew oil out of the IO-360 (CC363i) but never had it over 6 qt.

The oil sump is towards the back of the engine and the dipstick angles in and forwards. My gut feel is that pitch attitude would make little difference to indicated oil level. That seems to be supported by this image in which I estimated the dip stick angle.

 

[Neal]

I add 7 and that puts me at 6 where mine remains quite stable. I'm sure it's on the higher side but following what I know from CC.