How do i keep my old vehicle in good shape?

Don’t crash it

Change the oil when required and get regular tune-ups from a reputable place

Keep it out of the weather, change the oil, don’t drive it too much.

Use synthetic oil. There’s no better substitute and don’t ever allow your engine to be low on oil. And maintain the small stuff before it becomes big stuff.

Get some hydraulics and make it do a bunch of pushups.

Same answer I gave you the last time you asked this question.

Check everything you can see each week; check things like the air filter, frayed wires, leaking battery acid, etc. There are many how-to books to choose from, and I love my auto repair for dummies book; its excellent.