Hello,
I am wondering if any improvements have been made to VII's with respect to combustion chamber deposits.
I was reading an engineering manual of piston aircraft engines by Jon Schwaner, who mentioned the shearing of VII's but also mentioned that VII's have shown increased combustion chamber deposits due to oxidation and thermal decay. I have a Cessna 180 aircraft which has a Continental O-470 engine in it. In the winter, I used Aeroshell 15w50 semi-synthetic oil. In the summer, I prefer Aeroshell 50 weight oil to avoid shearing and combustion chamber deposits.
All of my reference materials are 20 years old or older. I had an article that was in an SAE publication where Shell Oil and Mercedes tested 10 wt, 10W30, and straight 30 weight oil were compared for cylinder wear rates. I seem to recall that the straight 30 weight oil showed the lowest wear rate in the cylinder wall and ring pack.
I am also wondering how to tell if synthetic oils have viscosity index improvers added, or not? I would expect a mineral based 10w30 motor oil to have a VII added to it. Is it likely that a synthetic based 10w30 oil would not have VII added?
When I lived in a very temperate climate, I used to use straight 30 weight oils in a VW Beetle air-cooled engine along with all the cars we had that specified 10w30 or 5w30 oil.
It is no longer practical to run straight weight oils where I live now.
I found the motor oil university on BITOG to be very helpful too.
Am I correct in my assumption that viscosity index improvers have gotten better over the years?
I am wondering if any improvements have been made to VII's with respect to combustion chamber deposits.
I was reading an engineering manual of piston aircraft engines by Jon Schwaner, who mentioned the shearing of VII's but also mentioned that VII's have shown increased combustion chamber deposits due to oxidation and thermal decay. I have a Cessna 180 aircraft which has a Continental O-470 engine in it. In the winter, I used Aeroshell 15w50 semi-synthetic oil. In the summer, I prefer Aeroshell 50 weight oil to avoid shearing and combustion chamber deposits.
All of my reference materials are 20 years old or older. I had an article that was in an SAE publication where Shell Oil and Mercedes tested 10 wt, 10W30, and straight 30 weight oil were compared for cylinder wear rates. I seem to recall that the straight 30 weight oil showed the lowest wear rate in the cylinder wall and ring pack.
I am also wondering how to tell if synthetic oils have viscosity index improvers added, or not? I would expect a mineral based 10w30 motor oil to have a VII added to it. Is it likely that a synthetic based 10w30 oil would not have VII added?
When I lived in a very temperate climate, I used to use straight 30 weight oils in a VW Beetle air-cooled engine along with all the cars we had that specified 10w30 or 5w30 oil.
It is no longer practical to run straight weight oils where I live now.
I found the motor oil university on BITOG to be very helpful too.
Am I correct in my assumption that viscosity index improvers have gotten better over the years?