I guess I will also need tips on what type/brand of auxillary oil guage to buy for the Loyale. I can usually hear if there is an oil pressure problem, but wouldn't mind a back up guage. Are they expensive? I want good quality, but am hoping it won't break the bank.

Your local parts store should have what you need. Less than $20. Maybe even a 3 gauge volts water and oil less than $20. Maybe Walmart. Just look to see if it looks Cheesey or flimsy. It should also have everything to hook it up with.

Your Loyale doesn't have an oil guage already? Not totally surprising, as Loyales are generally less well appointed than the earlier cars. But my Turbo Loyale has one, as do all of the earlier GLs. An option for you, assuming that yours is sans gauge, is to use an instrument cluster from a car that has the guage (and possibly other gauges) and install the oil pressure sender.

 

These cars really are just large "Lego" sets, so mixing and matching options is... well, an option. My Loyale lacked electrically adjustable mirrors, so I picked up some electric mirrors from the junkyard and replaced the non-electrics. Wiring was already in place. (Thanks again, dptyrob!!!)

It does have an oil guage, but I have been told that they are not very reliable.

Maybe not so much reliable as accurate. Accuracy is relative and subjective. The gauges themselves seem pretty reliable; I have not heard of anyone writing that there gauge has failed (but I am relatively new here). The sender units can be funky, and accuracy suffers with a sender unit that has been treated unkindly (they kind of stick out in harm's way). I have one whose body turns without the mount fitting turning, and this affects how the gauge reads (I can indicate negative pressure!!!), but a new sender unit (not too expensive from parts store) would fix that. They are far better than what Detroit put in their cars for years, and maybe still does. The parts are probably made by the same companies that make parts for Toyota, Nissan and Honda.

if your car has a gauge for the oil you have the large sending unit. there is a 1/4 inch plug on the oil pump that would be for the smaller oil sender for cars equipped with a dummy lite. this would be a good place to connect a mechanical gauge

 

if the fitting in your kit doesnt want to thread in(npt vs metric) you can get an adapter at auto zone, ask for it as its behind the counter in a tray, you can look and compare to the plug for thread

it's a good idea because sound is a terrible indicator of oil pressure. it won't work in the most critical situations. in slowly degrading situations tapping will start eventually and you can add or change oil or fix your seals. but if it's an instant blow out of a seal or oil pump gasket the block can very easily be destroyed (rods, bearings, seized...real bad) due to oil loss before the lifters make enough noise for you to catch it.

there is a 1/4 inch plug on the oil pump that would be for the smaller oil sender for cars equipped with a dummy lite. this would be a good place to connect a mechanical gauge

 

would my oil pump have this same port? i have an 89 gl-10 with the digi-dash, and i want to put in an oil pressure gauge.

would my oil pump have this same port? i have an 89 gl-10 with the digi-dash, and i want to put in an oil pressure gauge.

 

Yes, your car uses the smaller of the holes, with the larger one plugged