Determining oil change intervals via analysis

To rebuild a small airplane engine costs about $20,000 and takes months.
You don't want to do it unless you have good evidence that it is needed.

 

I was talking a top-end. That can be done in two days tops. And a full
overhaul doesn't take months. Where'd you get that? A good mechanic do
do that in 3 days. And many folks get a factory reman and that takes
about two days to do the engine swap.

Matt

 

I was of the impression that a major overhaul was mandated at so many hours
running time.. Was it 5,000 hours, or more?

 

2000 hours is a typical number. But so what? I would certainly have
an oil test done within the first hour on a new or rebuilt engine.

 

I am sure you would.

 

Only if the aircraft is used commercially. The typical TBOs are 1500 -
2000 hours.

Matt

 

Faith based car maintenance?

 

Hah. That all depends on how deep your pockets are. I've seen an
engine exchange ($$$$$$) in a commercially-owned single-engine tri-tail
bonanza. Total downtime was 3 days, but they prolly spent $25k on the
job in the mid 90s.

The biggest issue with general aviation aircraft is they're still using
100% manual engine controls. While our cars have advanced greatly in
engine management, airplanes are still dicking around with mixture and
carb heat knobs. All it takes is one descent with the mixture knob out
to destroy an engine. Or you run overrich and get crappy economy and
clogged up sparkplugs.

JS

 

sure! beats bothering to actually learn anything.

 

Once a year here, sometimes twice. Pine pollen season clogs them up
noticeably every time. Sometimes hay season can do it, too.

On my dodge truck, OTOH, which spends time on sand/silt roads and has
the worlds crappiest air intake design ever (it sucks air right off the
passenger wheel), its about 3x a year and I put about 1/3rd as many
miles on it.

JS

 

So... I take it nobody has seen that this cross posting bastuhd hasn't
replied to his thread????

"I'll have spam. spam. spam, spam, baked beans and spam"....

 

Not all airplanes. Check out Cirrus and other new designs.

Matt

 

Good point.

 

Agreed. I was referring more to the people who are absolutely convinced
that they must change their oil more frequently than the recommended
7500 mile intervals.

 

Makes me wonder what the ulterior motive was behind the original post.

 

"must"? No.

"Cheap insurance"? ABSOLUTELY. There is no cheaper insurance for an
engine than oil changes.

Figure out how much you want to pay for that insurance, and set your
intervals accordingly.

If you want to keep the car a long, long time, then 3K intervals (or
even 5K if you bought the car new and are using good oil) are extremely
cheap yet very effective insurance.

 

No, I dont regard ignorance and stubbornness as virtues. There are a
lot of people who are impressed by apparently highly technical data
and specifications, and who really dont know what, if anything, it means.

 

On every change, put a drop of oil on a piece of glass and check it under a
$2 10x eye loupe in strong light. You can easily see metal fines in the oil,
most of which are normal. You can determine if they're ferrous or
non-ferrous by passing a magnet underneath the oil drop. If you see larger
particles than normal, better get it checked out.

I'm guessing that antifreeze can be detected in oil with a $5 dollar black
light in a darkened room.

 

You would be surprised how easy it is to learn what the data means.

That said, it isn't worth it. It's cheaper just to change the oil.

 

You're right to a point.

However, engine failures are seldom directly oil-related. An engine usually
fails from part failure or abuse long before they wear out from infrequent
oil changes. By the time you start to see oil-related wear, a car is usually
very old, and has over 150K miles on it.

Rather than worrying about 3000 mile or 5000 mile oil changes, I worry about
things that happen suddenly, such as cooling system failure, cracked block
or heads, broken timing chain or belt, punctured oil pan, broken valves,
etc.