Just done a 25hr service, with 65hrs on the new engine. I have never seen plugs as clean as this. No oil at all, and more importantly none of the deposits which I always used to dig out of the bottom plugs.
The new engine is just another IO540-C4D5D so it can’t be the engine. The last flight was partly 85% power (150F ROP) and partly 65% power (peak EGT) with the final 30 mins at peak EGT which is how I normally fly. That was a 1hr flight and the one before that was a 6hr IFR flight which went up to FL190.
I had also noticed the same lack of plug deposits on the previous service (25hrs ago) but some plugs were oily.
The only difference I can think of is that the engine was running on Shell straight 80 oil, no additives, in accordance with the Lyco running-in recommendations. Normally I use 50/50 W80 and 15W50 and Camguard. That has just been put in so it will be interesting whether the next service will show plug deposits again…
I do not think this has anything to do with the oil you are using. This is just your new engine.
My plugs look like that all the time using 20W50 and Camguard (TSIO-550C)
I never understood why you had to dig out so much gunk from your plugs if you run at peak EGT.
20W50 is not Aeroshell 15W50. I too had deposits with AS 15W50 and switched to Phillips 20W50 and everything is a lot cleaner now.
I use only D80 (winter) or D100 (summer) + Camguard and my plugs look just as clean, almost no deposits.
I use whatever the cheapest oil I can get my hands on. Which is always Total. I never use multi grade and I use as much 100 weight oil as the temperature allows as it slightly cheaper than 80 (no idea why) and I would say I tend to use straight oil more often than dispersent.
I have 4 engines doing about 600 hours a year each. I guess about 50 percent of the continental cylinder heads make TBO and about the same success with Lycoming camshafts.
The one and only rotax with 2000 hours on it. Has supermarket 15/50 and it’s never used a drip in-between services.
The rotax plugs always look clean. The others less so. Some can be quite oily and the Lycoming frequently covered in lead. I don’t think the type of oil used makes any difference.
I have 4 engines doing about 600 hours a year each. I guess about 50 percent of the continental cylinder heads make TBO and about the same success with Lycoming camshafts.
@Bathman – do you mean you replace half your cylinders and half your camshafts within 3.5 years?
Continental cylinder head wise that is the case. Only 50 percent of our cylinder heads were making TBO.
Although we have had a change in policy. With the SDMP we were thinking of running the o-200 way over their current TBO. Maybe 4000 hours. So when the last o-200 was overhauled we had new crankcase, new crank, new camshaft, followers and new cylinder heads.
Of a course the CAA have a now said aircraft used by flying school have to stay on lamp for a further two years. So with a stroke of a pen we are 6 grand out of pocket.
Lycoming camshafts wise we are running at 100 percent replacement. As both the Lycoming powered aircraft needed new camshafts. The factor remastered one at 1200 hours and the other a norvic overhauled one at 2000. Although both those engines were only operated by us for about 100 hours before they failed.
I have a new data point which is very interesting.
45hrs airborne time since my previous post here, another service has been done. The plug condition is just as previously i.e. no deposits.
This time the engine had 50/50 W80 + 15W50, with Camguard! Just like I used to have before.
The 45hrs included a lot of higher altitude stuff e.g. UK to Croatia, UK to Greece, UK to Bolzano, UK to Menorca.
