I don't remeber seeing it before, my oil is quite old(about 3k miles) and I have no coolant loss?

anybody have any ideas?

 

Well, I guess my thermosensor may not bad at all, I have been running very cool at 78C or so, so this makes sense.

BTW, is I am acutually running cool, and thermosensor isn't faulty, what else could cause me to run cool?. I have new thermostat

From Felix Miata's FAQ:

What's that foamy stuff under the oil fill cap & inside the filler tube?

If you look closely, you probably also see water droplets mixed in or nearby the foam. If you find either, there is probably nothing you can do to permanently get rid of them. Luckily, you don't need to. A change in your driving pattern to include more driving under high load and fully warmed, and less driving of short trips or while the engine is cold, might do the job. Enough of such a change will do the job if your car is totally stock.

What you see is an emulsion, oil mixed with water. Your oil includes emulsifiers as part of the additive package. They cause water to actually mix into and "disappear" within the oil. To a point, they do exactly that, preventing small amounts of water from congregating in any one place that might result in oil starvation in a critical location. As long as the amount of water doesn't exceed the ability of the emulsifiers to disperse them, no harm is done.

All engines are subject to condensation from the normal heatup and cooldown processes, the same way dew forms on the grass in the morning. The oil filler tube area is subject to very little oil flow, and very little ventilation flow, while at the same time it is one area highly subject to the forming of condensation. The emulsifier in the little bit of oil in the area forms the foam as its limit to absorb the oil is reached. When the engine gets hot enough, long enough, the water will boil off. Whether this will routinely happen with yours simply depends on your driving patterns.

 

Exactly - And on RX-7 it is even more prevelant because of the long Oil filler neck w/ a couple of bends. The top of the Oil Filler neck stays fairly cool relative to the oil and so promotes condensation in the area of the filler cap. Also is worse in cold wet weather.

 

Phew that's it! Just checkin since it is a rotary I thought it meant that the primary axis flux capacitor attached to my mr. fusion blew and I needed ANOTHER motor. One less headache.

 

ROFL, that is some funny ****.

SO what do you guys think coudl cause me running so cool?

 

uhhh... winter in Canada, maybe?

btw, I don't think I've ever seen more tity bars in one place than in Montreal... just an observation.