Heretofore there has been no information in the POH about proper oil level for the CC340 though we have passed along instructions verbally to our dealers and to customers directly and I believe there is something in the Maintenance Manual provided with every aircraft. That is being rectified: language is being written and will be included in the next rev that all owners will receive. Until then though I thought I'd pass some info along.

As most of you know we fabricate and install our own oil sump rather than using the incredibly heavy Lycoming-style sump. Our sump is welded up from aluminum sheet, aluminum tube, and some laser-cut flat aluminum for the flange. The sump also is designed to hold less oil (further weight reduction). A standard Lycoming/ECi 4-cylinder engine likes to run a a 6 qt level. Yes, conventional wisdom is to fill it with 8 qts, but it will blow the top 2 qts off pretty quickly and settle in at 6. Since our sump holds 2 qts less the target oil level should be 4 qts. So, you can safely let it run down to somewhere below 4 qts and then add one. Since the sump holds less oil checking and maintaining your oil level becomes more important.

There is no question that increasing the oil quantity helps lower oil temp by spreading the heat over a larger quantity of oil. Adding a quart may lower your oil temp 10°. So, in hot ambient conditions consider running oil level a half to full quart higher.