fuel pump . Fuel getting into sump.

To my knowledge in the U.S. we only have un-leaded fuel. I have never heard of your type problem.

Maybe it is due to a certain fuel additive specific to your area.

I suspect that the fuel additives that are in your unleaded fuel are not compatible with the diaphragm material in your fuel pump. Try contacting the manufacturer of your fuel pump concerning the diaphragm problem.

Also, check with some of the companies that sell/make fuel pumps to see if their pumps are compatible with your fuel. An electric fuel pump would solve the oil dilution problem.

I would be concerned about all of the fuel hoses including the vent hose to the carbon canister. They may not be compatible with your fuel either.

I had heard that there were a lot of engine fires shortly after New Zealand switched to unleaded fuel (1996??). You don't want that in any car!!

Let us know what you find out.

Thanks guys will do