A Lyco rep has been quoted on the US Socata group as saying that with UL fuel, suggested oil change intervals are extended to 100 hours from 50, with an oil filter installed. Still suggested at four months’ calendar time, though. That doesn’t change.
Interesting! What are the views here? The obvious downside is fewer opportunities to detect gradually building problems, and spark plug checking.
The 4m calendar time makes this irrelevant for nearly all owners anyway.
UL94 apparently doesn’t exist in Europe – or perhaps anywhere else 
However some researches show than the oil starts to loose some qualities (like acid dissolving) just after 30-35 hours.
So I change every 25 hours but it’s just me being an orthodox:)
Peter wrote:
The 4m calendar time makes this irrelevant for nearly all owners anyway.
This is my situation. I run mostly unleaded, but don’t fly 50+ hours every 4 months. No idea why there is the 4 month recommendation, particularly if you keep the moisture out, and run unleaded…
Here is the official document from Lycoming
SL270 local copy
They allow you to change oil every 100 hrs but they still want you to change filter at 50 hrs.
This is of course possible to override in Part-ML if one wants to. We do it on the seaplane in our club to minimize downtime during the relatively short season.
On N-reg this service is not legally required anyway so one could choose.
Curiously I don’t see the rationale for changing the filter at 40hrs; that is the one item which should go to at least 100hrs! Especially if you go for the Challenger one.
The POH/maintenance manual for the Super Guepard with Rotax912 engine advises 100 hour checks if you use SP95 (unleaded 95 – mogas) but 50hr checks if you use Avgas 100LL.
AFAIK this is the same for all Rotax 912s so would suggest that the lead and carbon on tje plugs is the main deciding factor.
The number one problem with using 100LL is that the residue of the TEL has to be carried by the oil, as only the mineral content of the lubricant can hold the TEL residue in suspension oil change intervals are governed by this factor, so if you are using a semi-synthetic oil this TEL residue saturation point requires oil changes at 50 hours or the engine will start to have TEL residue build up in the engine.
Obviously the UL fuels don’t have TEL added so TEL residues are not a problem and in theory oil change intervals can be extended however as most aircraft suffer from under usage and the build up of corrosive substances in the oil calendar time to oil change is the big issue.
For those flying 50 hours a month this may be an advantage but for most of us the oil change intervals will remain the same.
I do suspect that those running engines past TBO and on condition UL fuel with extend cylinder life substantially as the TEL residue in high time engines is a big issue effecting oil consumption as this residue can have an adverse effect on the performance of the oil control rings.
Save as Raven, I change oil at 25 hours. I also like to change oil before the winter in order to have an oil with less acid contents when the aircraft is flown less.
I use UL98 whenever I can, 100LL otherwise, sometimes Mogas in my bird (Lyco O360)
Yes I saw.
Is that on SDMP?
