I have a first gen RX-7 that runs well, but after sitting for several days it burns a lot of oil for five minutes, then it's completely normal until it sits for a few days. I've suspected the OMP leaking oil into the carb when parked, but it doesn't sound like an OMP would/could be pressurized without the engine running. Any advice on what to look for? It's only after it sits for a while. On a positive note, I'm keeping the mosquitos down in my neighborhood...the neighbors don't appreciate it much.

 

Probably weak oil control rings, oil is seeping past from sitting and leaking into the chamber

I wouldn't worry about it until it starts smoking nonstop, just keep your eye on the oil level more

 

As a side note, the OMP can't leak into the carb. There is nothing to push it into the carb when turned off.

 

Do you premix?

Some types of two stroke will 'settle down' to the bottom of the gas tank if left sitting for a week or two. I thought I was always burning a lot of oil after letting it sit for weeks at a time, but I eventually figured out it was the premix settling. If I don't add premix before letting it sit, it doesn't smoke (much). Leave it sit for a few weeks with two stroke in the tank and it'll smoke like crazy, but I left it all winter with just a tiny bit of two stroke in the gas tank and it hardly smoked at all when I finally started it up.

 

Second vote for Oil Control Rings. These will typically last about 200k miles and gradually get stiff and lose sealing pressure against the side and center housings. Thse are the equivalent of the oil skirt ring on a piston engine, and will allow oil to seep past into the lower combustion chamber, usually getting ejected into your exhaust manifold on startup and burning off from there as the exhaust heats up. Some excess oil will spin around and help to lubricate your engine and also help to seal it during startup.

Be sure to check your oil supply regularly, as it will be consuming oil like a drunked sailor on leave. The only fix is a rebuild with new Oil Control Seals and their Springs.

 

You can try some oil additives like Lucas to make the seals work better. Its a known way to extend the life of and old worn engine.

 

Is a Lucas Oil additive OK to use on a 12A? This car only has about 74,000 miles on it and I don't want to make things worse.

 

74K, why thats just getting broken in. I'd change the oil and watch the coolant level and see how it goes first.

Did this car sit for long periods not being driven?