oil on bottom sparkplugs with slightly rough engine when power is reduced

[N2903l]

i was told by an IA to switch to aeroshell 15-50. it burns cleaner and fixed the rough engine completly

[aaronk25]

Have a hard time believing that would be the fix. I'm assuming you were using a heavier straight weight oil which if a engine is using a lighter oil it will pass more oil. 15-50w oil is lighter and would accelerate the oil burn which if the theory was right it foul the plugs quicker.

You must have changed something else besides the oil? It's normal for some oil to be on bottom plugs as these engines are pretty "loose".

[orionflt]

how many hours on your engine?, what are your compressions? and what type style and brand of spark plug are you using?

as your engine wears you can get more oil passing by the rings and valves, normally you will see an increase in oil consumption and indications of oil on the plugs especially if the engine sits for awhile in between flights. although your oil may be the cause of the issues you are seeing it is not the cause of the problem and changing brands or viscosity of oil will not fix the problem. you need to take a look at the overall internal condition of your engine. the reason for asking about the plugs is because the plugs you use can affect how well they burn off the additional oil build up.

REM38E are the standard plug you will find for your engine, I use a REM40E because it is a hotter firing plug and s acceptable for use on the same engine. on engines that tend to build up lead deposits REM37BY plugs are recommended or you could go with a fine wire REM37s. Fine wire plugs are more expensive but seem to have good reviews for extended service life and better firing in most applications. by changing your plugs to fie wire or REM37BY you will not aviod the oil problem but the plug will handle the build up better than the standard massive plug.

 

Hope this helps some.

 

Brian

[Alan Fox]

I have to disagree completely , If I run Phillips it burns twice as much as if I run Aeroshell , Don't ask me to explain why , but that's a fact.......

[aaronk25]

I have to disagree completely , If I run Phillips it burns twice as much as if I run Aeroshell , Don't ask me to explain why , but that's a fact.......

Hey is that Phillips 20w-50 or their 50w. I'm guessing its not their 50w as it's not as popular as shell 50w.

[Bob - S50]

Aeroshell 15w-50 is the one oil that Mike Busch does not recommend because it has too much synthetic oil.  The synthetic oil cannot carry lead like mineral based oils.  Don't know why it would reduce oil on the spark plugs.  Since synthetic does not break down over time and remains in longer chains, that could explain the reduced oil usage.  As time since oil change increases, mineral based oils would get thinner and slide past everything easier.  Synthetic would not.

 

As for running slightly rough when you reduce power...

Are you talking about pulling the throttle back but leaving everything else set?

Are you talking about leaving the throttle and reducing RPM?

Are you running ROP or LOP?

Are you sure the deposits are oil and not soot?

Have you tried one of Mike Busch's airborne mag checks? (I have not done that yet)

 

Bob

[PLN_FXR]

Aeroshell 15w-50 is the one oil that Mike Busch does not recommend because it has too much synthetic oil.  The synthetic oil cannot carry lead like mineral based oils. 

 

Bob

I haven't read what Mike Busch had to say about A/S 15w50, but it is roughly 1/2 synthetic.  Our local powerline patrol aircraft routinely make double TBO (4000 hours) on their O-320 & O-360 Lycomings running 15w50, so in my experience there is no operational issue with how it is formulated.  We run 15w50 in the flight school aircraft and have always made TBO plus - and not many aircraft get abused the way flight school aircraft do (idle to full power in less than a second; inadequate or no leaning resulting in excessive fuel burn & combustion by-products; etc., etc).  I would probably recommend Phillips to someone who doesn't fly much and is in a coastal area, as it is a high paraffin oil and the waxy residue it deposits inside the engine may help control corrosion - but otherwise would always recommend Aeroshell 15w50 or 100wPlus (the A/S "plus" straight weights have the same additive package as the 15w50).

 

Whatever oil you choose, just make sure you change it regularly and listen to your engine if it tells you it doesn't like it 

[KSMooniac]

Flight school and pipeline aircraft routinely make TBO or a lot more due to frequent use.  

 

There is a growing amount of evidence that the A/S 15W-50 and + variants do more harm than good, in terms of seal damage and leaching copper out of bearings from what I've read.  

 

I know my engine didn't like 15W-50...it was using that when I bought it, so I continued.  Oil consumption was fairly high, and when I switched to 80 or 100 it decreased noticeably.  I've seen others comment about much better oil analysis results once they got off the 15W-50 as well, but I wasn't that diligent unfortunately.  

 

You might search for comments here and other forums made by Ed Kollin, a lubrication engineer and inventor of Camguard.  He explains the "why" of what I wrote above.

 

Oh, and for the original poster, I can't imagine changing oil has anything to do with fouling of plugs.  What kind of plugs, how much time on them, and have they been tested for resistance lately?