CT9000 Posted May 25 Posted May 25 34 minutes ago, skippydiesel said: In over 10 years & 950 hrs of operation (almost no AvGas) my last 912ULS never had any "sludge" in the oil tank. In my early, amature, automotive, mechanic days, it was not unusual to have sludge in engines - no longer the case. I put this down to the use of high detergent oils and better engine temperature control.😈 Most of that grey paste like sludge was because of the lead in the fuel. Old in efficient engines do not burn all the fuel and so lots of pollution and oil contamination.
skippydiesel Posted May 25 Posted May 25 19 minutes ago, CT9000 said: Most of that grey paste like sludge was because of the lead in the fuel. Old in efficient engines do not burn all the fuel and so lots of pollution and oil contamination. So you don't think the change to high (relative) detergent oil in both petrol & diesel engines has anything to do with the lack of sludge? 😈
facthunter Posted May 25 Posted May 25 Rich running motors will darken the Oil. You will get Much more sludge when the engine runs too Cold. It takes over an hour in the air to reach stabilised temps on Most Motors. Idling Mixtures are Generally more rich than in flight. Engines leaned out Properly won't have a lot of soot in the Oil and I don't mean Lean of Peak. Nev
CT9000 Posted May 25 Posted May 25 17 minutes ago, skippydiesel said: So you don't think the change to high (relative) detergent oil in both petrol & diesel engines has anything to do with the lack of sludge? 😈 Dirty oil is not the same as the sludge build up. The sludge is largely products of combustion and contaminates not burnt. When you look at the combustion chamber of an old inefficient engine it is no wonder that pollution is so bad. The rings did not seal resulting in blowby. The oil has a big job to do.
facthunter Posted May 25 Posted May 25 Aircraft engines should NEVER be in that condition. They don't stay in service till they are worn out. (unless it's in a Swamp Boat.). Nev
danny_galaga Posted May 25 Author Posted May 25 1 hour ago, skippydiesel said: So you don't think the change to high (relative) detergent oil in both petrol & diesel engines has anything to do with the lack of sludge? 😈 Absolutely agree with you here. Case in point, my old air-cooled VW. Even though I was running it on unleaded, it would still build up some sludge, and that's because I was using plain oil, no detergents. Which is best for an engine with no filter. The sludge helps trap particles. 😇
skippydiesel Posted May 25 Posted May 25 41 minutes ago, CT9000 said: Dirty oil is not the same as the sludge build up. The sludge is largely products of combustion and contaminates not burnt. When you look at the combustion chamber of an old inefficient engine it is no wonder that pollution is so bad. The rings did not seal resulting in blowby. The oil has a big job to do. The detergent in engine oil is not about dirt per say, its about the ability of the oil to contain & suspend contaminants. In my limited experience: Detergent oils were first developed for diesel engines as a way to containe/suspend the high levels of soot. We were advised against using diesel/detergent oils in well used petrol engines, as it was thought that the detergent would clean the inside of the engine, such that clearances would increase, the engine would loose efficiency and possibly shorten its service life. Then we were told it was okay to use diesel oil in new petrol engines as they had yet to build up the layers of "beneficial"(?) varnish etc. Now we have detergent in most crankcase oils "suitable for diesel/petrol engines" Rotax recommended oils, for 9 series engines, are able to containe/suspend lead - is this detergent or some other system?😈
BrendAn Posted May 25 Posted May 25 i had a hilux work ute on a minesite years ago. it only ran up and down from the workshop to the pit so it never had any decent runs at op temp. a couple of times when i changed the oil i could hold the oil filter upside down with no oil coming out it would sludge up so bad. we would idle it on a mix of diesel and oil for 20 minutes then drop that and put new filter and fresh oil in. off it would go for another few weeks. 1
facthunter Posted May 25 Posted May 25 In the 90s Hilux had 5000 KM oil changes. I've often seen them when the oil would nor drain out the usual Drain Hole. Nev 1 1
facthunter Posted May 25 Posted May 25 Please enlighten Me Onetrack. I'm always ready to Learn, They recommended some different type of Oil.. I have NO axe to grind. Nev
BrendAn Posted May 25 Posted May 25 14 minutes ago, facthunter said: Please enlighten Me Onetrack. I'm always ready to Learn, They recommended some different type of Oil.. I have NO axe to grind. Nev i don't think he was having a go at your comment. more about how they sludged up so much. another place i worked at had a nissan 720 that was just as bad as the hilux for sludge.
onetrack Posted May 25 Posted May 25 I'm sorry Nev, there's no quote in your reply, so I'm at a loss as to what you need enlightening about. My last post in this thread was at 10:43AM Friday, and it read - "They may be painted to look like Rotax filters - but I'd have to opine, they're the filters that don't meet with Rotax approval."
facthunter Posted May 25 Posted May 25 There was something about ashless oils at the time the oil thickening was Happening. It was a SAD emoji from onetrack. I was wondering what was sad about it? Nev
onetrack Posted May 25 Posted May 25 The sad emoji was about people who own good vehicles, but fail to do even basic maintenance such as on-time oil changes. I've seen and had to repair the destruction caused by poor maintenance, I'm fixing an engine right now, that was abused to a standstill. Some people should never be allowed near mechanised equipment. 1
BurnieM Posted May 26 Posted May 26 Sad but true. A few US youtube videos with cars over 50,000 mi without an oil change. Oil changes are easy to do yourself and cheap. 3
facthunter Posted May 30 Posted May 30 People who don't change oil are cheapskate Drongo's. Bad oil will ruin the Best of engines, making them unreliable in the Meantime. Modern oils are More specific in their applications than was previously the Case.. 2 2
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