PetitCessnaVoyageur wrote:
What % of PAO does it contain ?
Why this choice ?
I see I changed my post and deleted the rationale for the choice…
Very simple: that’s what had been used in the engine since new, it is not AS 15W50, and it is 25% PAO and 75% mineral. Additional factors were that I needed to make a decision quickly, therefore did not take too much time to think it through, and the people I asked for advice told me to go for AS 15W50 
I’ve just ended my AS15W50 stock.
Oil analysis shows “anormal” low wear (than average). BUT a blow-by which is in average, or very slightly above.
I am thinking about going Phillips X/C 20W50, but not completely sure it is the way to go.
Blackstone advised me against, stating that nothing in the analysis was suggesting such a move.
For their part, they consider both AS 15W50 and Phil X/C 20W50 “good oils”
Just my penny…
Aviathor wrote:
and the people I asked for advice told me to go for AS 15W50
And you went against. I see your way of thinking… Subversive man 
PetitCessnaVoyageur wrote:
And you went against. I see your way of thinking… Subversive man
I thought someone might pick up on that…
Once you have chosen a guru (Mike Busch), why ignore his advice even if others say differently? It is the same thing with LOP engine operation.
Short of making your own laboratory experiments, collecting your own data and make your decisions based on that, all you can do is listen to and compare the arguments of people that claim being knowledgeable on the subject, evaluate the experiments they have made, evaluate their experience, their level of credibility, and then decide who you want to believe.
Aviathor wrote:
all you can do is listen to and compare the arguments of people that claim being knowledgeable on the subject, evaluate the experiments they have made, evaluate their experience, their level of credibility, and then decide who you want to believe.
EuroGA is my Church, so I thank all of you for your being here. Amen
More seriously: I completely agree with this way of proceeding… Looking for people who seem to be as far as possible from individual doxa.. And learning from them.
Peter wrote:
However I also suspect there is an element of “if we change our recommendations we will get sued because the previous ones will have been deemed wrong”.
If that was true, why would Shell sell the W80+, W100+ etc. (variants of W80 and W100) and Total sell XPD80 etc. which all include the Lycoming unleaded AVGAS additive?
Possibly because Shell don’t make engines. They merely need to be sure their oil isn’t going to damage anything.
Whereas Lycoming are continuously at the receiving end of lawsuits from engine owners whose engine “came apart” after a few hundred hours, etc. PROB99 due to the plane having been a hangar queen for years, probably under a previous owner who didn’t disclose it, and Lyco routinely settle these low level actions with some sort of “deal” involving a discounted overhaul etc. They don’t want anything big to blow up.
As my fleet utilisation has now risen to previously unseen levels I am becoming more convinced that most of the oils on the market are suitable for engines that get a lot of use, I’m changing the oil on my O-235’s at less than thirty day intervals and finding the filters to be very clean.
Currently I’m using Aeroshell W15/W50 and seeing the engines burning about 1USQ per 25 hours flying.
So the current conclusion is what most of you are looking for is the best oil to handle the lack of use of your engines and it would seem that the Lycoming SB advice that oil should be changed regardless of hours flown at four month intervals holds good as well as to keep a tight eye on the oil temp indicator calibration to ensure that you achieve 180F oil temp in flight to cook off the moisture that forms in the oil.
Low oil temp is a particular problem in Northern Europe with the C152 and the reaching the correct oil temp each flight is essential to prevent corrosion related problems, ironicly baffle rubbers in poor condition may well help to achieve this in the winter.
A_and_C wrote:
Low oil temp is a particular problem in Northern Europe with the C152
With more than the C152, I wager. I had to blank off a big part of our oil cooler (O-320) so that the oil would get up to the correct temperature. (IIRC Piper used to make “winterisation kits” for things like the TriPacer which did just this – blank off part of the oil cooler)
