Richgj3
BENEFACTOR
LI,NY
I use 15/50 Shell oil. I’ve been doing that since I hung a valve in an O-300 in the eighties and was using Phillips oil. The good old boy who fixed my cylinder (I was on my way to SNF) told me I shouldn’t use that because they had all sorts of valve problems in their O-200’s (same cylinders) and they switched to Shell 15/5O. I did and no more problems. I’ve learned that since then Phillips did recognize a problem and changed their formulation and their 20/50 gets good reviews.
My new to me C170B which sat for 13 years and flew less than 5 hours a year for many years before that, has had two stuck exhaust valves in the first 15 hours of flying. The first was an away game so it was left for the local FBO to do a cylinder change caused by an ignorant repair shop, but not important now. The second one happened at my home field. This airplane has 250 SMOH but a lot of years. It has always used Shell 15/50.
After several consulting calls and measuring the valve springs from the cylinder that was replaced (which were out of spec weak) we decided to do the rope trick on all the others and clean the guides and replace the springs on intake and exhaust. It turned out that two cylinders had exhaust valves so tight they could not be moved by hand with the springs off. The rest of the cylinders were ok. The A&P working with me used to build engines for Mattituck and I have known him for years and respect his opinion. We cleaned the guides and stems and all good.
He tells me the Shell 15/50 is known to cause sticky valves and I should switch to 20/50 Phillips. So we have come full circle. I’m curious if anyone here has heard this. I know oil choices are very subjective sort of like guitar strings and bourbon, but I welcome opinions.
Rich
PS: I use MMO and TCP now, but of course have no idea what was done before.
My new to me C170B which sat for 13 years and flew less than 5 hours a year for many years before that, has had two stuck exhaust valves in the first 15 hours of flying. The first was an away game so it was left for the local FBO to do a cylinder change caused by an ignorant repair shop, but not important now. The second one happened at my home field. This airplane has 250 SMOH but a lot of years. It has always used Shell 15/50.
After several consulting calls and measuring the valve springs from the cylinder that was replaced (which were out of spec weak) we decided to do the rope trick on all the others and clean the guides and replace the springs on intake and exhaust. It turned out that two cylinders had exhaust valves so tight they could not be moved by hand with the springs off. The rest of the cylinders were ok. The A&P working with me used to build engines for Mattituck and I have known him for years and respect his opinion. We cleaned the guides and stems and all good.
He tells me the Shell 15/50 is known to cause sticky valves and I should switch to 20/50 Phillips. So we have come full circle. I’m curious if anyone here has heard this. I know oil choices are very subjective sort of like guitar strings and bourbon, but I welcome opinions.
Rich
PS: I use MMO and TCP now, but of course have no idea what was done before.