What is the thread size in the engine where the sender installs npt1/8 or10-1 metric?
The gauge I have is 10-1 metric threads. I'm trying to make a remote with a greese gun hose npt1/8 and a npt1/8 female to female connector. The threads seem to be close but the 10-1 metric only screws on a few turns before it gets tight. Is this ok any help or thoughts. Do I need other adapters?

It's metric and I don't understand why people try to put an SAE hose in, although I don't know where to get a 10mm hose. 10mm...same as stock sender.

Yes, it's metric, but it's TAPERED metric. The oil pressure senders we can get are 1/8 pipe, which is so close to 10mm fine tapered that the difference just doesn't matter. THAT'S why we use 1/8 tapered hose.

The Cap'n