Based on the G100UL fuel leak thread what's your position?

[A64Pilot]

8 hours ago, Pinecone said:

Except that Lycoming has already published a Service Bulletin that doubles the oil change interval when using unleaded fuels.

I think that double the oil change interval is a significant increase.

And once 100LL is gone, synthetic oils will further increase oil change intervals, as they did in auto.  We went from 3000 mile oil changer intervals to over 15,000 miles.

The primary driver in extended auto oil change intervals is the extraordinary clean burn they have plus very reduced blow-by and nearly zero oil burn, when was the last time you cleaned the carbon off your plugs in your car?

Auto engines come out if the box with near perfect tolerances now, they require no break in etc now because of that.

You just can’t draw comparisons with auto engines, unless you compare to ones built just after WWII.

Yes I’m aware of the doubling of oil change interval and I’m certain doing so the engine will still make it past warranty.

But we don’t I believe know what the Gami fuel will do to oil either

Edited 5 hours ago by A64Pilot

[Justin Schmidt]

2 minutes ago, A64Pilot said:

The primary driver in extended auto oil change intervals is the extraordinary clean burn they have plus very reduced blow-by and nearly zero oil burn, when was the last time you cleaned the carbon off your plugs in your car?

Auto engines come out if the box with near perfect tolerances now, they require no break in etc now because of that.

You just can’t draw comparisons with auto engines, unless you compare to ones built just after WWII.

Yes I’m aware of the doubling of oil change interval and I’m certain doing so the engine will still make it past warranty.

Are we forgetting that auto manufacturers are still saying 6000 miles or 3 months

[GeeBee]

22 minutes ago, Justin Schmidt said:

Are we forgetting that auto manufacturers are still saying 6000 miles or 3 months

Not mine. Somewhere between 10 and 12K miles depending on the sensor or 1 year. Usually I time out before mileage.

[A64Pilot]

19 minutes ago, Justin Schmidt said:

Are we forgetting that auto manufacturers are still saying 6000 miles or 3 months

I don’t believe most do. way back in the 90’s or maybe earlier GM developed GMOLS or GM Oil Life System, it was an algorithm that started with some number and every cold start and other ops that was detrimental to oil life decremented some amount from the starting number, when it hit zero or near it anyway you were notified your oil needed changing.

They won several awards and I believe if it was Patented that has run out and most manufacturers followed suit

My personal take is oil is at its best when you pour it from the bottle, from there it degrades, extending oil change intervals is a fools game.  Auto manufacturers determine how bad it gets before it’s no longer doing the job, often marketing drives that number. For example back about 2010 or so the Prius had a 5,000 mile recommended oil change interval, and many environmentalists were slamming Toyota why if it was truly a “green” car wasn’t its oil change interval longer, so Toyota gave in and doubled it, either way it would easily get to the end of warranty. This from the company that had just gotten through the infamous sludge lawsuits.

But, I don’t see any of the couple of manufacturers of Aviation oil developing new Syn oils when UL fuel becomes the norm. I think the market is too small for the payback, and the Mobil-1  issue is too fresh.

I’ve always wondered why Exxon pulled out, I thought Elite was excellent from what I could tell. My belief is the small profit didn’t offset the liability.

Edited 4 hours ago by A64Pilot

[Justin Schmidt]

3 minutes ago, A64Pilot said:

way back in the 90’s or maybe earlier GM developed GMOLS or GM Oil Life System

I have seen that code, has nothing to do with actual oil life. It's actually really laughable what they do. Same of all "oil life monitors"

Gm manuals still say 6000. Hyundai up to a few years ago said 3 "rough" 6 otherwise.

Ultimately, it depends on condition. How you drive, type oil, environment etc. only oil analysis and bore scope will tell. Same for our planes. 

[Gary0747]

I am late to this discussion but wanted to throw in a couple of comments   I attended the presentation in Buckeye last year and asked the question about what testing had been done on our polysulfide fuel tank sealants.   I just got a cursory answer that it was currently in an airplane fuel tank with no signs of leaks.  I would like to see testing that might predict the long term effects on these sealants.   Perhaps measuring surface hardness readings or adhesion force measurements both over exposure time.  
Any new fuel that replaces lead and straight chain hydrocarbons with aromatic hydrocarbons like toluene, benzene, xylene, etc to maintain octane will be more aggressive on paint and sealants and some types of rubber.   The aromatics will typically increase the octane lost by removing the lead, but should have initially raised red warning flags in the development of this or any new fuel.   I would have thought it critical to test the long term compatibility effects on day one of any new fuel development project like this.  
I think polyurethane paints and sealants will better resist aromatic chemical attack than acrylic paints and polysulfide sealants