Recommend oil for rotary engine
Recommend oil for rotary engine
What oil can I use on my FD?….Stock, I’ve always used Castrol 20-50 non synthetic here in Florida….Is it possible to use a Synthetic oil with the stock oil injection system?
OR Get yourself the Rotary Aviation OMP adapter & plumb a simple gravity feed tank to it. Put the pre-mix lube of your choice in the oil tank and run synthetic oil in the sump. Best of both worlds.
Some synthetics burn ashless, though which ones are debated. It's pretty much accepted that Idemitsu's rotary specific is a synthetic that burns ashless - I've also had a client accidentally run many cases (over a few years) of VR1 synthetic when he thought he was buying the mineral version of VR1, on teardown it looked great but a sample size of 1 isn't enough for me to make a suggestion on.
Some synthetics burn ashless, though which ones are debated. It's pretty much accepted that Idemitsu's rotary specific is a synthetic that burns ashless - I've also had a client accidentally run many cases (over a few years) of VR1 synthetic when he thought he was buying the mineral version of VR1, on teardown it looked great but a sample size of 1 isn't enough for me to make a suggestion on.
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Yep .... Just remember "A daily revvin keeps the motor from going to rotary heaven".

Steve
Joined: Mar 2001
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From: FL-->NJ/NYC again!
For non-synthetic, Valvoline VR1 20w50 is what I'd recommend year round in FL. It has added ZDDP additive, which is important for a rotary engine because of the harsh environment, to include the rotor ring gear to stationary gear interface.
"A ZDDP additive (Zinc Dialkyldithiophosphate) is a crucial engine oil supplement, especially for classic cars and high-performance engines, that provides superior anti-wear and anti-corrosion protection, forming a sacrificial layer on metal parts like flat tappet cams to prevent premature failure, though its phosphorus content requires lower levels in modern oils due to emissions systems, necessitating these additives for older vehicles."
"A ZDDP additive (Zinc Dialkyldithiophosphate) is a crucial engine oil supplement, especially for classic cars and high-performance engines, that provides superior anti-wear and anti-corrosion protection, forming a sacrificial layer on metal parts like flat tappet cams to prevent premature failure, though its phosphorus content requires lower levels in modern oils due to emissions systems, necessitating these additives for older vehicles."
Don't use racing oils like VR1 that have additives like ZDDP, etc., if you are running a catalytic converter - they will ruin it in short order.
Last edited by DaveW; Dec 28, 2025 at 06:04 PM.
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