what is the best drill bit size for oil return.

[bkblazen2003]

if anyone has ever drilled their oil pan. which size did you use that worked with the least amount of leak.

 

[TimG]

Potentially you could drill any hole size you want.

What is probably the best thing to do to prevent leaks would be to drill and weld a bung in the stock location. Have a hydraulic shop fab up a line so that it could go from the turbo to the oil pan with the proper fittings. It beats all the issues of the dreaded oil return line leak.

 

[Defiant]

The usual repair size is ¼-20, whose drill bit size is a #7 bit, or 13/64"
Rather interesting that it's not ¼", but such is the world of machinery and woodworking.

 

[bkblazen2003]

ok. this is for the stock oil return pipe right?
i am not using an aftermarket braided line.

 

[BlackEclipse62]

Get a 3/8 NPT barb fitting with a 5/8 hose end on at lowes or just ask for a heater hose fitting and drill a 9/16 hole in the pan and use a 3/8 pipe threader. then take it to a local weelding shop and let them braize the brass fitting into the oil. It onlt take like 3 minutes to do and it only cost around 10 dollars, and you know that it won't leak. Good luck with your project . I just finish my oil ines today and installed the turbo tomarrow off the Muffler shop to make me a down pipe!