Question:
(Matt Adams) writes: As mentioned by others, the word is that synthetics in lead burning (aircraft) engines is probably not a good idea as sludge tends to accumulate. Also since aircraft engines, by design (correct me if I’m wrong, Greg), burn a little oil (hence the need for ashless oil) you would not want to use automotive oils in them.
I run Mobil 1 15W50 in my VW powered Sonerai with excellent results. I switched from the recommended straight 30 weight when I couldn’t hold oil pressure. The synthetic retains it’s viscosity and provides high heat protection. It also flows easier at low temp so pressure builds quicker to limit "dry" starts. I’ve been running Mobil 1 in my automobiles since 1986 and never have I failed to get 200,000 miles minimum out of each. Oh, the Sonerai burns 100LL and I have not had a problem with lead deposits. However, I drain at 25hrs as recommended for non synthetic oils.
Response:
- Hide quoted text — Show quoted text – The following is an article the old men brought in yesterday. The original contained pictures of the engine parts after teardown. I was going to make them change the oil this week to Mobile 1 15-50. Now I don’t know what to do. I’m guessing we might use Prolong and Duralube at this point. Here’s the article: ubject: LUBRICATES AND ENGINE TYPE? To: a little over 500 hours total time, about 465 of those hours were on Mobil AV-l oil. The engine was flown on an average of 140 hours each….. Bill, Its my understanding Mobil AV-1 had problems related to lead retainment due to the high content of it in aviation fuels. Running your V-6 on unleaded should pose no problems. As an aside, I remember reading an article comparing a variety of oils in automobiles. For normal use, the synthetics posed no significant advantage except you could go far futher between oil changes (that’s why I use it as I drive 40K/year). Rob (RV-6Q).
Check out this URL for some Mobil AV-1 info http://www.avweb.com/toc/maint.html You have to register but it seems to be painless. Jim
Response:
You might want to contact an amsoil distributor, they are rated four times better than mobile 1.
Better at what??? Who rated them "four times better"? Amsoil? — Matthew Greenlaw Mechanical Engineering http://hubcap.clemson.edu/~mgreenl Clemson, South Carolina
Response:
You might want to contact an amsoil distributor, they are rated four times better than mobile 1. Vince Thomas says… – Hide quoted text — Show quoted text – The following is an article the old men brought in yesterday. The original contained pictures of the engine parts after teardown. I was going to make them change the oil this week to Mobile 1 15-50. Now I don’t know what to do. I’m guessing we might use Prolong and Duralube at this point. Here’s the article: ubject: LUBRICATES AND ENGINE TYPE? To: By Ron Santosuosso I recently had the disheartening experience of witnessing the tear down of a Continental 520 engine. This particular engine was factory new with a little over 500 hours total time, about 465 of those hours were on Mobil AV-l oil. The engine was flown on an average of 140 hours each….. Bill, Its my understanding Mobil AV-1 had problems related to lead retainment due to the high content of it in aviation fuels. Running your V-6 on unleaded should pose no problems. As an aside, I remember reading an article comparing a variety of oils in automobiles. For normal use, the synthetics posed no significant advantage except you could go far futher between oil changes (that’s why I use it as I drive 40K/year). Rob (RV-6Q).
Response:
LUBRICATES AND ENGINE TYPE? To: By Ron Santosuosso
I have seen several articles on the pros/cons of synthetics over the years. One thing to keep in mind is that they are so slippery they don’t stay on the metal surfaces well. If the engines are driven/flown regularly then all is okay. But if it is used only once a month you might be asking for more trouble than the benefits one would be getting. I use Amsoil synthetics in the vehicles I use daily and it is a definatly better, but I won’t use them in my motorcycle or airplane as they don’t get used enough. Jim Peck
Response:
The following is an article the old men brought in yesterday. The original contained pictures of the engine parts after teardown. I was going to make them change the oil this week to Mobile 1 15-50. Now I don’t know what to do. I’m guessing we might use Prolong and Duralube at this point. Here’s the article: ubject: LUBRICATES AND ENGINE TYPE? To: By Ron Santosuosso I recently had the disheartening experience of witnessing the tear down of a Continental 520 engine. This particular engine was factory new with a little over 500 hours total time, about 465 of those hours were on Mobil AV-l oil. The engine was flown on an average of 140 hours each year. When Mobil pulled AV-1 off of the market, the owner opted to use Aeroshell 15W/50 as a replacement. During the flight following servicing the engine with Aeroshell 15W/50 the owner noticed abnormally high oil pressure. The high oil pressure continued for about a half hour during the two hour flight, then returned to high normal indiction. The engine oil and filter were changed and the engine wa again serviced with Aeroshell 15W/50. About this time the owner received information regarding the class action lawsuit filed on behalf of Continental owners who were using Mobil AV-1. It just so happened, the airplane was in for annual inspection. A decrease in compression was noted on all six cylinders. During the annual, an oil leak at the crankshaft seal was discovered and the propeller was pulled to replace the seal. The mechanic noted the propeller has an abnormally large amount of sludge built up in the hub. The quantify was described as "enough to make three golf balls from the sludge residue". Additionally, a small oil leak that had been plaguing the owner for sometime was determined to be coming from the oil pan to engine seal. When the oil pan was removed a significant amount of sludge had accumulated in the bottom. About 25 hours later, the aircraft was again in for maintenance and oil change. The owner requested the mechanic check the compression. The mechanic reported compression again had degraded significantly, however, it was within acceptable limits. At this time the propeller was pulled to measure the thrust washer clearance. Again, a significant amount of sludge was found in the propeller hub and the thrust washer clearance was found to be just barely within Continental service limits. The aircraft was returned to service. About 30 hours later the aircraft was in for maintenance and an oil change. A compression check revealed on cylinder was down to 15/80 other cylinders were in the 35/80 zone. The mechanic refused to return the aircraft to service. Three cylinders were initially pulled. As I describe to you the condition of the cylinders and other components you must keep in mind this engine was factory new with about 500 hours total time since new. The owner flew it by the book and it had frequent oil and filter changes, never exceeding 50 hours between oil changes. The first three cylinders pulled were examined and were found to be simply "worn out". In all three there was, for all practical purposes on choke, none whatsoever. One cylinder was mushroom shaped, The remaining three were in about the same general condition. The only was I can describe the piston is: to me it looked like a piston that had been run past TBO and came out of an engine that rarely saw an oil change and was run very hot. There was extensive ring wear, stuck rings and the pistons themselves were black between the top compression ring and forth scraper ring (Continental used a 4 ring piston the fourth ring being below the piston pin). In order to remove the piston the piston pins had to be driven out using a sawed off broom handle and mallet. The area around the pin between the rod end and piston had accumulated a brown colored ring of gook that had hardened (heat?). The connecting rod to crankshaft bearing clearance was determined by pulling by hand on the piston end of the rod while zeroing a dial indicator on the crankshaft end of the rod, then pushing on the rod at the piston end. Overall the rod bearings were found to be just barely within maximum service limits. This is not a true test of clearance simply because there is some residual oil between the bearing surfaces. Two camshaft followers were found to be moving (in and out) through a limited range. There was evidence in form of marks across the cam lobes faces indicating the cam was slapping the followers vis the followers riding on the cam lobes. Other cam followers had wear patterns indicative of a follower that was not rotating. Looking into the crank case area, a syrupy brownish goo was present everywhere. The connecting rods were "painted" with the same brownish goo. (Now I have a mental picture of what cholesterol looks like). When the connecting rods were removed from the crankshaft the rod bearings were worn to the pint that copper was exposed, several had deep crevices that were obvious to the casual observer. Mobil offered the owner replacement cylinder assemblies as a fix! No compensation for bottom end damage. Neither I or three other IA’s who examined the "carcass" were willing to slap six new cylinder assemblies on the engine and sign it off as airworthy. Mobil still claims AV-1 doesn’t cause any bottom end damage! When the turbo chargers were disassembled there was up to 1/8 inch clearance in the turbo charger bearings. Examination of the drilled portion of the crankshaft disclosed the same brownish goo found throughout the engine except on the crankshaft there were cooked chunks similar to what was found on the piston pins. The owner bought a factory new engine $$$$$, with the hope that someday he would be able to get some compensation out of Mobil. Guy’s don’t use synthetics or part synthetic oils in you aircraft engines! Aeroshell l00W/80W or Phillips 20W/50W as climate dictates.
Response:
- Hide quoted text — Show quoted text – The following is an article the old men brought in yesterday. The original contained pictures of the engine parts after teardown. I was going to make them change the oil this week to Mobile 1 15-50. Now I don’t know what to do. I’m guessing we might use Prolong and Duralube at this point. Here’s the article: ubject: LUBRICATES AND ENGINE TYPE? To: By Ron Santosuosso I recently had the disheartening experience of witnessing the tear down of a Continental 520 engine. This particular engine was factory new with a little over 500 hours total time, about 465 of those hours were on Mobil AV-l oil. The engine was flown on an average of 140 hours each….. Bill, Its my understanding Mobil AV-1 had problems related to lead retainment due to the high content of it in aviation fuels. Running your V-6 on unleaded should pose no problems. As an aside, I remember reading an article comparing a variety of oils in automobiles. For normal use, the synthetics posed no significant advantage except you could go far futher between oil changes (that’s why I use it as I drive 40K/year).
Bill, Rob’s got it right. AV-1 was not able to hold lead in suspension so it ended up precipitating out all over the subject engines. The situation was not helped at all by the fact that Mobil’s marketing literature claimed you could/should go a hundred or more hours between changes. As for the superiority of synthetics, I’m starting to have my doubts as well. Those interested might want to check out a bogus little "study" I did – it’s on my web page at: http://gtravis.ucs.indiana.edu/Engines/Copper.html Of relevance to this discussion is that I could see NO difference in overall engine wear rates between an aviation semi-synthetic multi-vis oil and an aviation straight-weight mineral oil. greg —
Response:
Several paragraphs snipped… However, if it was my RV-6 (don’t I wish) with a Vortec engine, I would be inclined to use synthetic oil and burn only unleaded fuel and monitor the situation. It would be my believe (as in poorly educated guess) that the synthetic would be better in a high demand situation.
Trouble is, when you fly somewhere and need to refuel, you’ll probably have to take on a load of 100LL. At home, I fuel my Tri-Pacer from my own 55-gallon drums of unleaded regular mogas (the Tri-Pacer has an STC), but when I fly cross country, I invariably have to gas up with whatever the airport has at the pump. Usually 100LL, because few airports have mogas or the first alternative for the Tri-Pacer, 80/87 avgas. Something to consider in the light of what we now know about lead, sludge, and synthetic oils. It’s always a good idea to operate with a system that allows the most options. Mike
Response:
I’d say NOT. I have read article after article both pro and con and it is clear to me that 100% mineral with its additives do a better job of scavenging lead and products of combustion. Aeroshell seems a good compromise due to its high mineral oil content. BUT, automotive oil will keep your water cooled engine in better shape than aviation oil. I have had discussions with friends who have tried to run aviation oil in their automobile and both air and water cooled motorcycles(they worked at airports and could get the oil at cost). Rust inhibitors in aviation oil(and this was a use of Aeroshell)do not seem to work as well as those that are in automotive oils. I know that some oil guru will argue but I was told that when the engines were gone into all the internal steel and cast iron surfaces had a light rust layer on them. Once the engine is broken in, Prolong sure looks good in the infomertials. — Bruce A. Frank, "Ford 3.8L Engine and V-6 STOL