I have a stock oil sending unit setup on my 289 that is spraying oil at cruise RPM...essentially 2500RPM and above. Here is what I have tried, two OEM steel extensions from the block and three new OEM style (one NOS) sending units. I have tried multiple sealing types as listed below with these parts. Using a high volume Melling oil pump. Oil pressure is around 60psi. I laid under the car while my son held the engine at 3000RPM. I could see the oil spray up onto the bottom surface of the sending unit and onto surrounding surfaces. The oil is not coming out of extension/block connection. My next two tests are Permatex Black RTV and then just plugging the extension to test if it's the extensions or the sending units. As supplied out of the box teflon tape on new unit Taped with teflon tape ARP teflon based thread sealant paste Loctite thread sealant Teflon tape and Loctite thread sealant Permatex Aviation Form-A-Gasket All leaked and still leaking. Any ideas?