Problems with Multivis more likely......
Randy,
Oil is one of those highly contested subjects amongst wrench benders, just like wheel landing vs 3 point in the tailwheel circles.
I used to earn a living as an A&P (and then decided I needed more $$ so I could afford to fly and buy a house). This was 20 years ago, and I was working in a freight operation where we had approx 15 piston twins: Navajo's, Aztecs, Barons. All the aircraft flew approx 100 hours a month. My boss decided to save $$ on burned out starters in the winter months, so we switched away from the straight weight Aeroshell 80 (40 weight) and went to he (then) new Phillips multi vis. Yeah, we did save on starters burnt out, but our cylinder costs went way up. So, the shop floor manager had a barrel of two of Aeroshell stashed away in the back. Whenever we have an engine that has low compressions and high oil consumption, we'd switch it over to the straight weight Aeroshell. 100 hours later-compressions were back up and oil consumption was way down.
To this day, I only run straight weight Aeroshell in my aircraft engines. I used to subscribe to Aviation Consumer and they did an exhaustive test of av oils. As far as viscosity breakdown, they all were about the same. The only conclusion that I took away from the test was in the rust prevention dept. Multi vis oils scored better in the rust prevention dept. So, the advice from the author was if you don't fly often, then run multi vis, or if you fly in and out of hot and cold climes, you might want to run multi vis. Other than that, they left the conclusion open.
So, I run 100W in summer and 80W in winter. When I go up north, I take a pre-heater with me to warm the crankcase when it gets below 32F.
I hope that this doesn't start a flame war, I'm just stating what I learned first hand, and that was 20 years ago. I'm no oil guy, but based on the Av Consumer article, representatives of all the oil companies were contacted and it appears that most of the data presented was sales hype.
Oh, I seem to recall that approx 8 years ago, Shell had a bad lot of straight weight oil that had some dirt or contaminant. A service bulletin went out in the Av press and it was isolated to specific oil lot numbers. Perhaps the flight school your friend is speaking of got ahold of some of that bad oil.
Art in Asheville
'66 Mooney C model
2007 RV-8 (flying soon!)
