Strange residue on oil filler neck FC turbo
 

Ok, i have a 1989 rx7 turbo 2. When i've check the oil filler neck i've noticed a strange residue on the filler cap and neck. Greenish/yellow in colour.
I suspected a seal faliure of some sort ( not too familar with the rotary). My thought was the residue could be coolant leaking into oil. Is this possible?

Other than the residue, the oil pressure is fine, coolant is fine with no drop in level and no signs of oil in coolant.
I resently did an oil change and the oil looked, felt and smelt fine.

Another brain wave i had it could be H2O from combustion, Exhaust gases could be entering into the oil, This must also mean a seal faliure of some sort surely or is the rotary just that poor at creating a good seal?

I could just be trying too hard to find fault at my recent bargin purchase. Please help.

Ive had this too. I think its normal or O.K. I see no other problems.
And this is on a rebuild.
Ive Got 15k miles on rebuild.

It's normal if the oil on the dipstick is all...oil.
If you get the chocolate milkshake stuff on the oil dipstick, the engine is no good.

The crap on the oil filler cap is just condensation.


-Ted