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By Rob L
#1751016
WingedSupra wrote: <snip> My...C172 has an O-300-C engine...


On an unrelated matter, I have been servicing an O-300-A over the last few days. I'm no expert....but does your O-300-C have two sump plugs (one each fore-and-aft of the carb)? If so, make sure your maintenance company remove both during oil changes.

Rob
By WingedSupra
#1751098
Rob L wrote:On an unrelated matter, I have been servicing an O-300-A over the last few days. I'm no expert....but does your O-300-C have two sump plugs (one each fore-and-aft of the carb)? If so, make sure your maintenance company remove both during oil changes.


Cheers Rob. I'll have to check that. The a/c is very new to me and we've not changed the oil yet. I do know there are two oil screens at the back of the engine, and at least one sump plug down that end too. I have also had conflicting advice from two different engineers with regard to the oil change frequency, one recommends 25 hours due to the lack of proper filter, the other says 50 hours is fine!
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By Rob L
#1751198
WingedSupra wrote:
Rob L wrote:On an unrelated matter, I have been servicing an O-300-A over the last few days. I'm no expert....but does your O-300-C have two sump plugs (one each fore-and-aft of the carb)? If so, make sure your maintenance company remove both during oil changes.


Cheers Rob. I'll have to check that. The a/c is very new to me and we've not changed the oil yet. I do know there are two oil screens at the back of the engine, and at least one sump plug down that end too. I have also had conflicting advice from two different engineers with regard to the oil change frequency, one recommends 25 hours due to the lack of proper filter, the other says 50 hours is fine!


There should be a suction screen (aka "rock catcher") which operates on the suction side of the oil pump (low pressure) and a pressure screen which operates on the high-pressure side of the oil pump. Sometimes, there is fitted an after-market canister-type paper oil filter (like what is fitted to most Lycoming-powered aircraft). This is the case with the 0-300-A that I I am dealing with at the moment.

I'm tempted to ask the Mods to split our discussion to a new thread, because although talking about the same engine, you & I are discussing a separate issue, but it's worth sharing in the wider community. I have a few thing about oil change frequency too, but I think that's best for the same separate thread.
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By Rob L
#1751203
Rob L wrote:I'm tempted to ask the Mods to split our discussion to a new thread, because although talking about the same engine, you & I are discussing a separate issue, but it's worth sharing in the wider community. I have a few thing about oil change frequency too, but I think that's best for the same separate thread.
Ask and ye shall receive, so thanks! :thumright:
For the avoidance of doubt, here is the original thread about Mogas

Rob L in the above link wrote:I have a few thing about oil change frequency too, but I think that's best for the same separate thread.


So my point is to WingedSupra:
WingedSupra wrote:I have also had conflicting advice from two different engineers with regard to the oil change frequency, one recommends 25 hours due to the lack of proper filter, the other says 50 hours is fine!
If you have a Tempest or Champion full flow pressure filter on your 0-300, then yes, you can go to a 50-hour oil & filter change. But with a brass screen, 25 hours between oil changes is still recommended (and best practice).

I do hope that helps (probably not!) but keep asking here, and someone will chime in with info that will help us all learn.
By WingedSupra
#1751204
Rob L wrote:If you have a Tempest or Champion full flow pressure filter on your 0-300, then yes, you can go to a 50-hour oil & filter change. But with a brass screen, 25 hours between oil changes is still recommended (and best practice).


So, those would be spin-on filters using an aftermarket kit, right? I definitely don't have that. Just the 1962 screens :)

Now I'm being cheeky but would you know where I might look for a SB or similar which states 25 hours is recommended?
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By Rob L
#1751208
WingedSupra wrote:Now I'm being cheeky but would you know where I might look for a SB or similar which states 25 hours is recommended?

It would not be a Service Bulletin...it should be in the basic Maintenance Manual for the engine / aircraft you own.

Depending on the age of your aircraft, it would not surprise me that it doesn't say anything at all! My 1946 maintenance manual tells you nothing!

But Mick W & I are in agreement (along with 99% of the English-speaking world): 25 hours for oil screen; 50 hours for filter.

Hope that helps!

Rob
#1751286
Maybe 25 hours was valid in the 1950's, but oil technology has taken quantum leaps forward during the intervening 60-70 years...Witness the many yintage and veteran vehicles which are far -less wear-prone now, than they were in their early life..

Irrespective of filtration, it's amazing now many ferrous particles a sump-plug magnet will attract. I'd be tempted to add a magnet (Araldite to the rescue!) to any Aviation engine. :wink:
#1751347
cockney steve wrote:Maybe 25 hours was valid in the 1950's, but oil technology has taken quantum leaps forward during the intervening 60-70 years...Witness the many yintage and veteran vehicles which are far -less wear-prone now, than they were in their early life..

Irrespective of filtration, it's amazing now many ferrous particles a sump-plug magnet will attract. I'd be tempted to add a magnet (Araldite to the rescue!) to any Aviation engine. :wink:


I also add a magnet to all my sump plugs as you do. It's amazing the "fuzz" collected every oil change, largely from the cylinder bores I assume.
It won't collect "white metal" (babbit) from the bearing shells, or metal from the bungs on the ends of the piston pins (a pressure filter will collect these of course...everyone cuts open their pressure filters, don't they!)

Modern cars all have a magnet in the gearbox for the same reason.

Rob