While not an A&P, over twenty years of owership of various airplanes has taught me a few things. First, oil is cheap, and change it often. Even if you have an oil filter, change it every 25 hours. I don't know where to get it any cheaper, but you might try the Shell distributor in your area to see if you can buy cases direct. We use Aeroshell 100 (50 wt.) in our coupe for a couple of reasons, especially in summer. Multigrade oil is thinner, and if you have the typical oil leaks, multigrade will leak more. Also, we get better consumption on straight weight oil. We were going thru multigrade like you know what thru a goose, but since our annual last month, and the shift to single grade, we haven't burned any in the first 5 hours. Unless consumption gets rediculous, don't worry about a quart every 5-6 hours. There are other important criteria of the engine's health, and take your A&P's advice. Also, our oil temp. is a tad lower with single grade. Since we are in a heated hanger, I don't worry too much about it in winter either. But if your plane sits out, or is in a cold hanger, and if you have cold winters, you may want to use multigrade in winter, even though you pre-heat the engine. Jerry Eichenberger Columbus, Ohio N2906H
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