Declan and TCP???

[NC Bill]

Is it better to use 100LL with DECLAN or without?

 

If using DECLAN do you still adhere to 25 hr oil changes?

 

Is DECLAN better than TCP?

 

Sorry for the basic questions. But THANKS for your help.

 

Bill

[coppercity]

Also if your using a lot of 100ll, use a oil that works well with it like Aeroshell Sport plus 4, and not a full synthetic.

[Roger Fane]

TCP is a much more caustic chemical mix than Decalin. TCP comes with warnings to not carry it in an aircraft in order to avoid exposure to it. Decalin is ok to carry, but put the bottle in a ziploc bag to avoid spillage from pressure changes.

[FastEddieB]

Absolutely use Decalin with your 100LL.

 

I normally run MOGAS about 90% of the time, just throwing in AVGAS on trips when its not convenient to find MOGAS.

 

I'm planning a trip to S FL for next week, in which I'll probably just us AVGAS for the next 14 hours or so.

 

Can you please inform me of the alleged benefits of Decalin? And how much is used? And where might I order it from to get it here by the middle of next week?

 

Thanks!

[FastEddieB]

Thanks, Roger. I have a bottle ordered from Aircraft Spruce with expedited shipping.

 

One question...

 

It calls for 1/2 oz for every 10 gallons of 100ll.

 

Clear enough, but suppose you just added 10 gals of 100ll on top of 10 gals of MOGAS. Would you just add 1/2 oz (my guess) or just go ahead and put in 1 oz, given the 20 gals total in your tanks at that point.

 

My logic is that 1/2 oz would be enough, given that you just have 50% 100ll in the tank, so the ratio of Decalin to 100ll would be correct.

 

Or am I overthinking this?

[FastEddieB]

Back from the trip to S FL. Mostly went well. One "pucker moment" that I still need to report on later.

 

In any case, this is the first longer trip I've made where I gave up on the MOGAS logistics and just went with 100ll once my initial tank of MOGAS was consumed. Figure roughly 15 hours of flying at mostly 5,200 rpm or so and about 70 gals of 100ll mixed with Decalin.

 

No performance difference I could discern, but I really didn't expect any. I did notice that the inside of my exhaust pipe seemed much lighter in color - a very light grey, almost white:

 

 

(the horizontal scratches are from a ground clip)

 

Today I went and pulled and inspected my plugs:

 

 

 

The plugs are lighter in color than usual, but still look good to me, though the single plug above had a tiny deposit you can barely see between the center electrode and the insulator. And, in spite of how it looks in the photo, I am careful not to get the heat transfer paste on the bottom few threads - the whiteness there is deposits that brushed off easily, NOT errant paste.

 

Anyway, is that lighter color a side effect of either the 100ll or the Decalin? Normally plugs this light would indicate a slightly lean mixture, but nothing else has changed.

[FastEddieB]

Hi Eddie,

 

Looks normal to me with 100LL.

 

Thanks, Roger.

 

I still plan on using MOGAS locally and whenever feasible cross-country, but its good to know the engine seems to handle 100ll plus Decalin without any apparent undue ill effects.

 

I WILL probably go ahead with an oil change a little earlier than normal - maybe 30 or 35 hours instead of my planned 50 - since I'll be back on the good stuff going forward, at least 'til my next cross-country.

[sandpiper]

I think the instructions are to go to the shorter maintenance intervals if you use 100LL more than 30% of the time. From what you indicate, this 50 hour oil change will have 15 hours with 100LL. So, since that is equal to but not exceeding 30%, I'm with Roger. However, in the overall scheme of things oil is cheap. If you feel better changing it then go for it.