Optimal oil level

[bob888]

I'm curious to know what most RV10 owners consider an optimal oil level for their IO540 engines. Mine seems to drift down to about 7 qt fairly quickly after a 9 qt oil change and than remain fairly constant. I worry that may be too low when starting out on a long flight.

[lr172]

I don't have experience with a 540, however, most Lycomings quickly blow out oil filled above the optimal level (optimal meaning what the engine likes or will tolerate, not what Lyc recommends) The fact that yours quickly drops to 7 qts and presumably stays there for a while, would indicate that 7 qts should be your max fill. My 320 recommends 8 qts, but any more than 6 gets blown out, so I fill to less than 6 and add a qt when it drops to 4.

What is your oil consumption rate? Your engine will probably run fine on 2 quarts or less (I speculate that you'll still be pumping oil down to one qt, but don't have data to back that up). If you are burning a quart every hour or two, I would be concerned that 7 qts is not enough for a long trip. This is simple math. If you have 7 qts and your minimum is 2 qts (or use Lycomings recommended minimum level, which is 2.75 qts), you can figure out the risk of running low with your current oil consumption rate.

Assuming proper cooling capacity and reasonable blowby/oil consumption, bigger engines don't need more oil than smaller engines. My 496 CI big block holds around 4+ quarts. About the same as the 180 CI in my wife's Honda.

Larry

[CDN]

My O-360 was happiest at 6 qts when the max is 8 so I assumed that 50% more engine would require 50% more oil. You know what they say about assumptions, well, anyway this was wrong.

I was filling my IO-540 to 9qts but quickly found out that it would blow 2 qts out on the belly relatively quickly, even with an antisplat air/oil seperator. I now fill to 7 and add at 6. Mine will go about 13-15 hours before needing a qt at this level.

[greghale]

My RV10 is happy running at 6 qts. Checked with Blackstone about this and they said I might see an increase in oil temperature. Haven't noticed this.

[woodmanrog]

Our IO390 is happiest with 6 qts on the dipstick. We burn about 1 quart every 25 hours. Oil and filter changes at 50 hour intervals.

[Bevan]

Originally Posted by woodmanrog

Our IO390 is happiest with 6 qts on the dipstick. We burn about 1 quart every 25 hours. Oil and filter changes at 50 hour intervals.

That's pretty good! What oil brand/weight are you using? My older 0-360 seems to burn 1 Qt in 12 hrs when using Aeroshell W100plus but 1 qt in 6 hrs when using Aeroshell W80plus.

Bevan

[RV10inOz]

Most RV10 owners I know have a similar experience to mine. Fill to seven quarts, and top up at six. Any more and it blows overboard.

[N520TX]

Originally Posted by RV10inOz

Most RV10 owners I know have a similar experience to mine. Fill to seven quarts, and top up at six. Any more and it blows overboard.

My O-540-A1D5 runs this way as well.

[TomSpencer46]

Interesting. My new thunderbolt is hung but I have not done a first start yet. The dipstick is marked 12QT capacity. Should I only put in 7?

[Guy Prevost]

Originally Posted by RV10inOz

Most RV10 owners I know have a similar experience to mine. Fill to seven quarts, and top up at six. Any more and it blows overboard.

Same here. I've been wondering about this too. Glad to know mine seems to be in family.