Oil drain size on a little turbo T25 i think
 

I am reading Max Boost by Corky and he states the oil drain size should be big, like 1/2 inch ID or so. I was all set to install a #4 line (1/4 or so) from the drain to the pan and now I am wondering if I need to make it bigger. ? What do you guys run?:confused:

too small. bigger turbos don't use much more oil than little turbos. stick with 1/2 or larger

1/2" translates to -10 AN line. You can get it locally most the time at any hydraulic shop. It doesn't need to withstand high pressure just high heat. The oil drains via gravity so you want the easiest unrestricted drain flow possible.

I installed a -6AN braided stainless line for my drain, and I don't feel it's draining adequately due to some recent slight oil wetness around the center section. I didn't know of the recommendation of -10AN oil return plumbing (and apparently I overlooked the sizing suggested by Corky in Maximum Boost).

That said, I'll be installing a -10AN braided stainless line before the car is running again. As they say, do it right once!

Actually -10 is 5/8" id, -8 is 1/2" id which is what I sell. I wouldn't go much smaller than 1/2", but I think it is plenty large, since you have to use a 1/2" NPT at the pan anyway.
-Michael-

I always go with -10 and tap the pan 1/2" NPT.

Thanks again everybody, much appreciated!

The -4 line works great for oil and water lines going to the turbo.

Stick with a -8 or -10. :)
Stephanie