I'm backdating the gauges on my '48 GMC 1 Ton and need to change out the oil fitting at the block that supplies oil to the gauge as well as to the oil filter. There is a 90* brass fitting that threads into the block with one outlet feeding the gauge and the other outlet going to the oil filter. The oil filter connection will have to be removed first and I'm wondering how big a mess I'll be making when it's disconnected. I'm guessing the outlet to the gauge would only leak out under pressure but I could easily be wrong.
What should I expect? Thanks, Jim

All you can expect will be a little drip unless you or someone starts the engine. Then you will have a big mess.
George

Put a couple of rags under the fitting to catch the drips. There won't be much, but the line going to the oil filter will dribble enough to make a mess unless you raise the end of the line above the level of the filter housing. If you pull the top off the filter canister and remove the element first, there will be a lot less mess to deal with.
Jerry

Hahaha George, even I know better than that! And thanks, Jerry, I didn't think of removing the element but I will now. I'm always learning something new on Stovebolt.