How many oil changes/hours before oil analysis?

poadeleted21

poadeleted21

Touchdown! Greaser!
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Aug 18, 2011
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I'm about to do my second non-mineral oil, oil change. Should I send in the oil or wait till the next? I did 2 break in oil changes with mineral oil (they were brief) then a 50hr run of Exxon Elite.
 
Since this is your first full run without the last one being mineral oil, I would do one at this point.
 
Marauder said:
Since this is your first full run without the last one being mineral oil, I would do one at this point.
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I would too... This is the perfect time to get a baseline for oil analysis tests to come.....IMHO.
 
send it.

You can always decide to ignore the results later. It's a bit harder to send it for analysis later if you've discarded the oil.
 
General assumption with oil analysis is to send it in every oil change if you're going to bother. This is how you establish patterns so you can decide when something needs to be looked at closer.

I think there is some use to it, but I haven't been sold on it like I am on items like engine monitors, preheaters, and dehydrators (which reminds me - I need to make some for the plane still). As such, it's not something I do.
 
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I've never done it, just didn't want to scare myself with any residual break in metal should I decide to send it in, I'm not sure what I should be looking for after oil change number 1. I didn't want to send in the mineral oil because of the shock it might have given me.
 
If you use Blackstone, the questionnaire includes data for TSMOH, oil type, etc. they include a verbal analysis/commentary and will take all those factors into consideration. They've seen it before, you won't be shocked...not unnecessary anyway.
 
I do oil analysis, but reading the results is not always straight forward. I had a sample come back with higher than normal silica (dirt). So I had my mechanics inspect the entire induction system, air filters, etc. It was winter and my flying wasn't in especially dusty places, nothing found, so.....

I took another sample next oil change, all is well.

No explanation, just some money spent for an inspection.

I also notice the results change with the type of flying you do. For example lean cruise will give one result, high power/rich training will produce another. It makes it hard to react to a questionable sample.

The other thing to note, while Blackstone, etc list the number of hours between changes I'm not sure they rationalize the contamination against the hours vs. the fleet averages. For example if you always change at 20-25 hours you'll probably always get better than fleet average results.
 
Alexb2000 said:
I do oil analysis, but reading the results is not always straight forward. I had a sample come back with higher than normal silica (dirt). So I had my mechanics inspect the entire induction system, air filters, etc. It was winter and my flying wasn't in especially dusty places, nothing found, so.....

I took another sample next oil change, all is well.

No explanation, just some money spent for an inspection.

I also notice the results change with the type of flying you do. For example lean cruise will give one result, high power/rich training will produce another. It makes it hard to react to a questionable sample.

The other thing to note, while Blackstone, etc list the number of hours between changes I'm not sure they rationalize the contamination against the hours vs. the fleet averages. For example if you always change at 20-25 hours you'll probably always get better than fleet average results.
Click to expand...

This is the reason why I don't bother. With so many variables, you can either spend a bunch of money chasing your tail and not get anywhere, or just pay attention to symptoms in the early stages. I've found the latter to work well.

I don't tell folks not to, it's just not something I've seen as potentially getting benefit form.
 
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