Several customers have asked me detailed questions about not only which oil to use, but about the proper oil change regimen for the CC340 including break-in. Of course the maintenance manual that comes with each aircraft has our recommendation on oil and change intervals but doesn't go into
why, so questions remain, and inquiring minds want to know more. Below is an overview of our recommendation which we've developed in concert with ECi who provides our engine components.
Oil
We recommend
Philips 20W-50 XC ("blue bottle") from break-in right through TBO. This is a multi-viscosity mineral-based lubricant (non-synthetic). Philips does make a non-AD (ashless dispersant) version of this oil that they call 20W-50 M ("black bottle") which would be their version of a traditional "mineral oil" used for break-in, but we recommend the XC. The reason why XC can work for break-in is because it does not have the Lycoming LW 16702 anti-wear additive and thus allows a bit more friction to occur which is necessary for the break-in process. The ashless dispersant additives help keep the engine clean during break-in.
Change intervals
10 hours (10 hr interval)
25 hours (15 hr interval)
Every 25 hours thereafter
Long term
Though it isn't in the maintenance manual we recommend the use of
CamGuard in addition to the Philips 20W-50 XC
once the engine gets 80-100 hours on it and oil consumption has stabilized. This will result in simply the best protection you can get both in terms of anti-wear and anti-corrosion. Note: due to the lower oil capacity of the CC340 you only need a half bottle of CamGuard, so one bottle will last cover two oil changes.
Now, for those like me who want to know even more I've attached several articles from Aviation Consumer, arguably one of the best and most thorough aviation publications in the business, that gets in the technology and test results.
Hope this helps, good reading!