Just to share a couple of specs from auto engines: Engine oil needs to have viscosity matched to temp range, the lower the "W" number the lower the temp it is designed to handle. 5W30 is the best for really cold temps AND for all modern small oil port engines. The 5W allows it to still flow in temps around 20-25 degrees below zero F. 10W30 is your best all around oil grade. Only goes down to 10-15 below, but has better durability in warmer weather, up to about 100 degrees F. 10W40 needs to be reserved for areas like Florida, and Arizona, Southern California where the engine will see constant temps 75-85 and above. It can handle as low as the 10W30 but goes up to around 120 degrees F. 20W50 should only be used when severe duty is called for, or temps are regularly hitting over 100 degrees in daytime. It can handle up to approx 150 degrees F. It can only go down to approx 15 degrees above zero though so its use in winter is NOT recommended. In between grades may show good oil pressure numbers but will not flow throughout the engine as well as a lesser grade designed for the temp. Remember, we are using auto engines. The engine does not know it is in the plane, only the temps it is being asked to run in, and the work it is being asked to perform. Good oil pressure is 10 pounds per 1000 rpms. So at cruise 35-45 psi is good. Idle at 700-800 with 10-15 psi is good, as long as this is hot oil pressure. It should always be higher at startup. Higher oil pressures risk starving the bottom end by pumping the oil pan dry, especially if you do not have an over sized oil pan. The original manufacturer matched the oil capacity with the oil pressure/flow so that this would not be a problem. Make sure not to use a high pressure high volume oil pump with out increased capacity, or you may starve the bottom end bearings with all the oil pumped to the heads during higher rpm operation.
Mark, 15W40 might be a little too thick of an oil for the weather you are currently having. I would go with 10W30 or even 5W30 as long as you have snow on the ground, or the potential anyway. Remember, you are also cooling way off as soon as you climb out, so take that into account also. Not too much longer and I will join the Corvair crowd in the air! Colin crain...@cfl.rr.com http://kr-builder.org/Colin/index.html KR2(td) N96TA Sanford, FL Apex Lending, Inc. 407-323-6960 (p) 407-557-3260 (f) crai...@apexlending.com
